Fly agaric mushroom (Amanita muscaria). It is powerfully hallucinogenic, 
containing the drugs ibotenic acid and muscimol. The effects are unpredictable, 
and a few deaths have been attributed to this mushroom. It takes its name from 
the medieval practice of breaking the caps into a saucer of milk in order to stupefy 
flies. It is commonly found amongst birch trees in temperate regions in autumn.