Panaeolus acuminatus

Panaeolus acuminatus, also known as Panaeolus rickenii is a common little brown mushroom.
This species contains small amounts of serotonin (licit tryptamine), 5-HTP, and tryptophan.
Description.
This is a little brown mushroom that grows on dung and has black spores. It has a cap that is less than 4 cm across, hygrophanous, conic to campanulate to plane, usually with an umbo. The gills are dark purplish black, crowded, with several tiers of intermediate gills. The spores are (11) 13 - 15 (17) x 9 - 11 (12) x (6.5) 7 - 8 (9) micrometers, smooth, black, and shaped like lemons. Cheilocystidia present.
Habitat and distribution.
"Panaeolus acuminatus" is a mushroom that grows in grass and in dung. It has been found throughout North America and Europe and is very widely distributed.