Summary:
Features include 1) a bell-shaped to nearly hemispheric cap that is hygrophanous dark cinnamon to dark smoky gray, 2) adnate to adnexed, close gills that are pallid to dark, 3) a cartilaginous, pruinose stem that is pale ochraceous or cap-colored, 4) growth in grassy places, 5) a black spore deposit, and 6) microscopic characters. Some but not all collections contain psilocybin. Smith(5) in 1972 moved this taxon to Psathyrella castaneifolia (Murrill) A.H. Sm. but the combination is not universally accepted. The online Species Fungorum, accessed April 9, 2016, gave the current name as Panaeolina castaneifolia (Murrill) Bon, and MycoBank, accessed the same day, gave all three names in equivalent fashion. It is rare in the Pacific Northwest.

Cap:
1-3(4)cm across, distinctly bell-shaped at first, soon nearly hemispheric, then convex, and becoming broadly convex when old, margin incurved when young; hygrophanous, dark smoky gray, drying to more straw yellow or pale ochraceous, remaining more reddish brown at top and smoky brownish along margin; sometimes finely wrinkled, margin slightly striate, not appendiculate, (Stamets), 1-4cm across, convex, never fully expanding, margin incurved when young; hygrophanous, dark cinnamon, drying to pinkish buff; smooth, often wrinkled, margin even when young, translucent-striate when moist, no veil remnants, (Menser), 2-4cm across, convex, not fully expanding, margin incurved, when old often broadly conic; hygrophanous, dark cinnamon to dark fuliginous when moist, pale ochraceous and somewhat zoned when dry; often rugose [wrinkled], margin even, translucent-striate when moist, (Smith)

Flesh:
thick, firm, (Menser), rather thick and firm; fuligineous when moist, pallid when faded, (Smith)

Gills:
adnate to adnexed, close, thin; pallid, becoming dark purplish gray-black, (Stamets), adnate to adnexed, subclose; pallid, darkening to chestnut when old, edge white, (Menser), adnate to adnexed, not crowded, broad (0.6-0.7cm broad), triangular or ventricose; pallid to dark fuscous or castaneous ("Verona brown" Ridgway(1) color), edges whitish, (Smith)

Stem:
4-6(7.5)cm x 0.3-0.4(0.6)cm, equal to more narrow toward base, hollow, brittle; grayish to ochraceous or tan at base; slightly striate, pruinose, (Stamets), 4.5-7cm x 0.4-0.6cm, straight and slightly tapering toward base, base not enlarged, stem hollow, cartilaginous; colored as cap but may be lighter near the top when young; finely powdered, no veil remnants, top striate, (Menser), 4-6(9)cm x 0.4-0.6cm, slightly narrowing downward, cartilaginous, hollow; pale ochraceous or more or less colored as cap; pruinose, (Smith)

Veil:
no veil remnants hanging from margin (Stamets)

Odor:
mild, or rather strong, (Smith)

Taste:
mild or unpleasant, (Smith)

Microscopic spores:
spores 12-15 x 7-9.5 microns, [presumably elliptic], finely rough, [presumably with germ pore], pleurocystidia few or absent, not projecting beyond plane of basidia, cheilocystidia 20-28(35) x 7-10 microns, (Stamets), spores 12-16 x 7-8.5 microns, +/- elliptic in face view, somewhat inequilateral in side view, roughened, somewhat truncate from colorless apical germ pore, basidia 4-spored, 24-28 x 10-12 microns, colorless in KOH; pleurocystidia "present as dark cinnamon-brown basidiole-like bodies" 18-24 x 6-10 microns, embedded in hymenium, cheilocystidia abundant, 24-38 x 7-10 microns, "fusoid-ventricose to subcylindric, neck often flexuous and apex typically obtuse", thin-walled, colorless, smooth; clamp connections present, (Smith)

Spore deposit:
black, or also referred to as very dark purplish gray-black (Stamets)

Notes:
Panaeolus castaneifolius occurs in WA, QC, and NY, (Smith(5)). Paul Kroeger has deposited collections at University of British Columbia from BC and WA.

EDIBILITY

sometimes slightly hallucinogenic due to psilocybin contained by some but not all collections, (Stamets)

Synonyms and Alternate Names:
Panaeolus castaneifolius (Murrill) Ola'h
Psathyrella castaneifolia (Murrill) A.H. Sm.
Psilocybe castaneifolius Murrill