Pileus (Cap): 1 - 3.5 cm in diameter, obtusely conic to convex, and the margin is initially turned inwards, later becoming broadly convex to flattened or somewhat umbilicate while retaining a slight umbo, and at times quite irregular. The surface is viscid when moist from a gelatinous pellicle, but soon becomes dry and shiny, translucent-striate, and decorated with fine fibrillose veil remnants near the margin, often with greenish stains near the margin or a greenish tinge overall. It is cinnamon brown to dingy brown when fresh, hygrophanous, and soon fading to dingy ochraceous buff to cinnamon buff. The flesh is thin, pliant, bruising blue, sometimes slowly.
Lamellae (Gills): Close to crowded, narrow with adnate to sinuate to uncinate attachment. They are light brown at first, becoming rusty cinnamon as the spores mature; the edges are whitish and slightly fimbriate.
Stipe (Stem): 3%u20136 cm long, 1.5%u20133 mm thick, equal to enlarging downwards, tough, and is whitish to buff at first. The stipe is pallid to bluish when dried, becoming dingy brown towards the base with age, and bruises blue, sometimes slowly. The surface is powdered at the apex, and covered with whitish to grayish fibrils downwards. The flesh is stuffed with a pith and is solid at first but becomes hollow It lacks an annulus but sometimes remnants of the thin cortinate partial veil form a soon disappearing fibrillose annular zone in the upper region of the stem.
Microscopic features: Spores are dark purple brown, ellipsoid, 7-10 x 4-5 um from 4-spored basidia, thick-walled, and with a broad germ pore. The spores from 2-spored basidia are larger. The basidia are 2- and 4-spored. Pleurocystidia are absent. The cheilocystidia are 18-35 x 4.5-7.5 um, langeniform (swollen at the base, narrowed at the top), and with a thin neck, sometimes forked, 1%u20142.5 um broad at apices.
Season: June through December.
Habitat and Distribution: in deciduous forests on hardwood slash and debris, plant matter, on or about decaying hardwood logs, birch, beech and maple. Psilocybe caerulipes grows in eastern North America, from Ontario to North Carolina, and west to Michigan. It has also been found as far south as Mexico. It is often overlooked as just another little brown mushroom, and although widely distributed, it is not found often. It is sometimes confused with the larger Psilocybe ovoideocystidiata.