Panaeolus acuminatus

Panaeolus acuminatus, also known as Panaeolus rickenii, is a species of mushroom in the family Bolbitiaceae.

This species contains small amounts of serotonin, 5-HTP, and tryptophan.

Description
P. acuminatus is a small brown mushroom that 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
P. acuminatus grows in grass and dung. It has been found throughout North America and Europe and is very widely distributed.