Psilocybe atrobrunnea (Lasch) Gillet Cap 1.5-5cm across, conic-campanulate or convex; dark reddish brown, becoming blackish brown with age; pale tan when faded, margin striate when moist, smooth, viscid. Gills adnate, crowded, broad; pale cinnamon buff, then dark violaceous brown when mature. Stem 60-120 X 2-4mm, equal, flexuous, fibrous; covered with pale fibrils, becoming darker brown from the base up with age. Flesh thin; pallid. Odor slight, mealy. Taste mealy. Spores ellipsoid, smooth, 9-12.5 x 5-7µ. Deposit deep purple brown. Habitat gregarious in swamps and bogs. Frequent. Found in northeastern North America. Season August-October. Not edible, reported from Sweeden to have some hallucinogenic action, all hallucinogenic mushrooms can be dangerous to eat.