A genus of mushroom that produces the bitter-tasting indole alkaloid psilocybin that causes hallucinations and other side effects. Sometimes Psilocybe mushrooms are referred to as psilocybin mushrooms.

Often referred to as "magic mushrooms", this fungus contains two hallucinogens named .psilocybin' and 'psilocin'. There are a number of other poisonous and hallucinogenic mushrooms.

Psilocybe is a cosmopolitan genus of small mushrooms, best known for its species with hallucinogenic properties, widely known as "magic mushrooms" or teonanácatl (literally "god mushroom" - agglutinative form of teó(ti) (god) and nanácatl (mushroom) in Náhuatl). Though best known from Mexico and surrounding regions, these mushrooms are consumed worldwide. Psilocin and psilocybin are the hallucinogenic compounds responsible for the psychoactive effects many species Psilocybe.