Lepiota and allies are known for white spores, free gills, and often scales on the cap that can't be removed (unlike the similarly defined Amanitaceae that have a universal veil that may leave warts, which unlike scales, are removable). Unfortunately, some species violate all three of those generalizations. All species seem to have some sort of obvious partial veil. Species in this family often have a coloured "eye" in the cap disc where the scales are especially dense. Like Amanita, some of them have evolved to produce the deadly Amatoxin and can kill you if you eat them. Others are eaten regularly, especially some Shaggy Parasols (Chlorophyllum) although one species of that can be dangerously poisonous as well. While most Amanita are mycorrhizal, most 'Lepiotaceae' are saprophytic.
Many 'Lepiotaceae' are closely related to the Agaricaceae. Some are actually in that family (Leucoagaricus, Leucocoprinus, Chlorophyllum, Macrolepiota, representing Agaricus that lost their spore pigment. Laccaria is also a genus of white spored mushrooms in the dark spored clade of agarics that lost their spore pigment). Other 'Lepiotaceae' are closely related, in their own family, Verrucosporaceae (Lepiota, Cystolepiota, Melanophyllum and Echinoderma).
Some genera not only lost their spore pigment, but also lost the free gills that many of their relatives have, meaning that sometimes the gills are attached to the stem. That makes them a bit more difficult to identify as 'Lepiotaceae', but the scaly caps help. However, that's far from foolproof as other scaly genera exist that are similar but totally unrelated, like Tricholoma (which often will have specifically notched gills and seldom have a partial veil, unlike the mushrooms on this page). These attached gilled species are in their own family, the Squamanitaceae, except for Cystodermella which is by itself.
To complicate things further, three genera re-evolved coloured spores (or never lost all their pigments) - Phaeolepiota (pale yellow- to orange-brown, described not here, but on the brown spored pages), Chlorophyllum (one has green spores) and Melanophyllum (green or red!). That explains these rare spore colours not otherwise found.
Chlorophyllum and Macrolepiota - the largest mushrooms, 15cm or more across. These are the shaggy parasols with scaly caps, of which we have three relatively common local species. Formerly the differences were not recognized and they were all just called Macrolepiota rhacodes. Luckily, our climate is usually too cool for the very poisonous look-alike Chlorophyllum molybdites, with green spores (from where we get the genus name, which means "green gilled"). That species is mostly found south and east of us, but it has been found in Washington!
Cutting Chlorophyllum will turn the flesh bright orange! (but not in Macrolepiota). They have a well developed ring on the stem that can usually be moved up and down.
Do not confuse with Leucoagaricus americanus, with a spindle shaped stem, different looking scales and staining yellow, orange or red.
C. olivieri - the entire cap is brownish, without any bright white visible underneath the scales. More rural.
C. brunneum - Contrasting cap from the bright white under brown scales. Very abrupt bulb on the stem. More urban. May not have scales when young!
This is what young C. brunneum looks like before the scales develop on the cap. Note the crazy bulb.
C. molybdites - very poisonous species in grass with a green tint to the mature gills from green spores! Stains duller orange-brown than the others.
Echinoderma - medium to large species with erect scales on the cap and staining colours, all pretty rare. Although it is reported that our species are E. asperum and E. eriophorum, our species are probably undescribed.
Echinoderma spp. group - dark brown scales, rather cold colours. Some may exude a juice when fresh. They may have variable amounts of white showing between scales, and the stems may vary in scaliness.
Leucocoprinus - the smallest (<5cm across) and most delicate Lepiotas with a well developed ring and granular scales on the cap and somewhat on the stems. They have striate margins, resembling the smaller inky caps in stature. These are usually more tropical species, and found more often in greenhouses and potted plants than in the wild, although some species manage to grow wild in the summer months. Very closely related to Leucoagaricus and possibly not deserving a genus of their own (they are "inside" Leucoagaricus instead of "beside" it), but they are distinctive.
L. brebissonii - with a black eye in the disc, in the wild in warmer weather. 'Lepiota' atrodisca is similar but less delicate with a black edged ring and more fibrillose cap scales.
L. heinemanii - larger, more fibrillose black scales without as distinct an eye, found in greenhouses.
L. cretaceus - all white with a more copious powdery covering than L. cepistipes but still more granular than species of Cystolepiota.
L. birnbaumii (luteus) - a yellow L. cepistipes, found in flower pots.
L. flavescens - duller yellow
Cystolepiota - small (<5cm across), often more cottony overall than scaly with a poorly developed ring. The shagginess will wear off with age, however.
C. petasiformis - larger (>2.5cm) white species, copious veil material often forming a false conehead. Smells farinaceous.
C. oregonensis ('hetieri') - very cottony, turns orange-brown where handled! <2.5cm. Possibly DEADLY.
C. fumosifolia - larger (>2.5cm) with yellow-olive-brown discolouration.
Melanophyllum haematospermum is rare and has green or red spores and free red gills, a unique spore colour perhaps representing an intermediate stage between the dark brown of Agaricus and the white of Lepiota.
Melanophyllum haematospermum - red gills when young, fading and then harder to ID. Well developed veil. Green or red spores depending on how fresh the mushroom is.
First, the large species.
L. 'fuliginescens' - our sister species is more slender with a longer stem than the real CA species. Somewhat velvety brownish scales on a white background. Flesh stains orange-red (occasionally yellow) when damaged or old.
These species turn red where touched, sometimes dramatically so. Once I actually jumped backwards and gasped it was so startling.
These species have reddish brown fibrils that radiate out from the centre instead of breaking up into individual scales or concentric circles like most other species.
These species have pink or black scales on the cap, or they could be pure white.
'Lepiota' decorata - medium beautiful pink scaled species. Not yet moved to Leucoagaricus. Also consider the deadly Lepiota subincarnata.
'Lepiota' atrodisca - black edged ring, small, but not as delicate as the more coarsely scaly Leucocoprinus brebissonii. Southern species. Not yet moved to Leucoagaricus.
Some species of Leucoagaricus resemble small Lepiotas and will be very difficult to identify as Leucoagaricus. For instance, the rare 'Lepiota' oculata and Leucoagaricus ophthalmus, with Lepiota cristata-like brown scales on the cap. We have other undescribed species as well.
First those with sharp scales on the stem.
L. castanea group - small, eye and scales are warm brown. Sharp scales on stems. DO NOT EAT. Without ring. Three similar species found so far, L. 'castanea', L. 'pilodes' and an unnamed one.
Next, those with a shaggy stem with cottony scales.
L. magnispora - medium sized, shaggy-stemmed Lepiota usually with a distinct, dark eye. DEADLY? Large spores.
L. ventrispora - very similar inland desert species found once in Idaho.
L. clypeolaria - similar, without the dark eye, but with the same poorly defined ring and large spores. Here most of the stem scales have rubbed off. DEADLY? Compare L. subincarnata.
L. erminea group (alba) - an albino L. clypeolaria, but with cap somewhat smooth. Smaller, less developed ring and a slightly shaggier stem than Leucoagaricus leucothites. Larger than other white species.
Finally, those usually with a smooth stem, most easily confused with the small Leucoagaricus.
L. cristata group - the classic urban (usually), small Lepiota. Orange-brown eye with a slight umbo and concentric scales. A strong, odd scent.
Cystoderma carcharias (fallax) - the only species with a well developed sheathing ring. Form fallax is orange. Form carcharias is a rare albino form.
C. jasonis - similar, slightly darker orange, brown tint to the gills and cap flesh.
C. gruberianum - clay brown species on Doug fir logs needing study.
Cystodermella granulosa - reddish-brown, gill edges smooth. C. ambrosii is a name incorrectly used for the albino form of this mushroom.
Floccularia - another genus with attached gills, these larger mushrooms (up to 15cm across) also have shaggy scales on the cap and on the stem. These are especially like the ringed Tricholomas, so look there too.
F. albolanaripes - dark scales on the cap.
F. luteovirens is rumoured to occur here, with pale scales and microscopic differences.
Tricholoma focale (zelleri) - bright orange colours, somewhat farinaceous. The most similar Tricholoma.
Lastly, possibly the oddest gilled mushrooms in the PNW. They are usually small (<5cm across).
Squamanita parasitizes other mushrooms, sometimes growing right through them, with the top part being Squamanita and the bottom part the original mushroom. They are very rare, purple and scaly and related to the Cystoderma mushrooms they often parasitize. Finding one would be quite an accomplishment.
And that completes another of the most beautiful groups of mushrooms found around here. Unfortunately there is not recent specialized literature with colour photos and up to date information for the PNW.