commonly known as the fly agaric or fly Amanita,
is a poisonous and psychoactive basidiomycete fungus.
Native throughout the temperate and boreal regions of the Northern Hemisphere,
Amanita muscaria has been unintentionally introduced to many countries in the
Southern Hemisphere, generally as a symbiont with pine plantations,
and is now a true cosmopolitan species.

It associates with various deciduous and coniferous trees.
The quintessential toadstool, it is a large white-gilled, white-spotted,
usually deep red mushroom, one of the most recognizable and
widely encountered in popular culture

from: Wikipedia