Panaeolus bisporus
Panaeolus bisporus, also known as Copelandia bisporus is a rare and widely distributed little brown mushroom that bruises blue and contains the hallucinogen psilocybin.

This mushroom is similar macroscopically to Panaeolus tropicalis, Panaeolus cambodginiensis and Panaeolus cyanescens, but can be differentiated using a microscope by its two spored basidia.

Description 

This is a little brown mushroom that grows on dung and has black spores.  It has been found in Hawaii, Southern California, North Africa, Spain and Switzerland.