This mushroom is probably the most widely recognized of all fungi. It's the bright red one with the white dots, the little dancing mushroom from Fantasia, the toadstool seen on hundreds of black light posters. It's gorgeous, it's big, it's hallucinogenic, and it's all over the place.
Amanita muscaria is common throughout most North America, Europe, and Asia. It grows in forests and at the edges of them. It shows up from fall to early spring in my area (Pacific Northwest), and can be as large as a frisbee when expanded. It's called Fly Agaric because the mushroom was mixed with milk in ancient times to poison houseflies.
A. muscaria is probably best known for its hallucinogenic properties. Indeed, it was used by some cultures for that purpose. The first Hindus in India actually worshipped the mushroom as a god. It is believed by some to be Soma, the mysterious divine plant of Vedic history. The Koryak tribe of Siberia realized the psychoactive properties of the fungus when it was passed through the body into the urine. They apparently drank the urine to get its effects.