 Panaeolus olivaceus

Panaeolus olivaceus is a widely distributed, seldom identified, little brown mushroom that contains the hallucinogen psilocybin; it is often mistaken for "Panaeolina foenisecii" and is distinguished by its black spore print and darker gill coloration when mature alongside a slightly thicker stem.It is even more easily mistaken for "Panaeolus cinctulus" or "Panaeolus fimicola" and can be distinguished from them both by its slightly roughened spores.