Panaeolus papilionaceus var. papilionaceus

'Panaeolus papilionaceus var. papilionaceus', also known as Agaricus calosus, Panaeolus papilionaceus, Panaeolus campanulatus, Panaeolus retirugis, and Panaeolus sphinctrinus is a common and widely distributed little brown mushroom.

This mushroom is the type species for the genus Panaeolus.

Description
This is a little brown mushroom that grows in horse or cow dung and has black spores. The cap is up to 5 cm across, grayish brown, not hygrophanous, conic to campanulate in age. The cap margin is adorned with remnants of the partial veil. The stem is 10 cm by 2.5 mm, fibrous and pruinose. The gills are adnexed and close, with one or two tiers of intermediate gills.

Some collections are mildly psychoactive, containing psilocybin.