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

[citation needed] 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 spores are (11) 13 - 15 (17) x 9 - 11 (12) x (6.5) 7 - 8 (9) micrometers, smooth, black, and shaped like lemons.

It has been found throughout North America and Europe and is very widely distributed.