Collybia alkalivirens Singer Cap 1-4cm across, broadly convex becoming flatter or broadly umbonate; margin incurved at first, then plane or recurved or wavy in age; dark reddish brown to blackish brown, fading to dingy pinky-brown or buff; smooth, moist to dry, margin radially lined to furrowed. Gills adnate, close to distant, narrow to broad; same color as cap. Stem 25-75 x 1-3mm, hollow, often flattened above; dark reddish brown or blackish brown; smooth, fibrous-brittle. Flesh thin, pliant; same color as cap. Turns greenish to dark olive with KOH. Odor none. Taste very bitter. Spores narrowly ellipsoid, smooth, nonamyloid, greenish with KOH, 5.4-8.6 x 2.2-5.4ì. Deposit white. Habitat singly or in groups on soil, moss, or very rotten conifer wood. Often common. Found widely distributed in northern North America. Season May-,July in the East, October-December in the Northwest. Not edible.