The whitish stem, which sometimes has an enlarged bulb at its base, is circled with concentric ridges toward its base, a very important identification characteristic.
This mushroom is poisonous, but not deadly. The Koryak people, nomadic, shamanistic, Siberian reindeer herders, traditionally used it to hallucinate, although the poisons would leave them quite ill afterwards. Then they'd drink their urine, which contains the hallucinogen, to get high again. When that no longer worked, they'd drown their symptoms in vodka.
The Aztecs would feed the mushroom to their warriors to make them braver.
Aspects of Santa Claus were allegedly inspired by this mushroom. His red coat and white buttons symbolize the red mushroom with its white patches. Santa flies because the mushroom sometimes creates the hallucination of flight. He uses reindeer because they're fond of the mushroom, and herders who eat reindeer that have eaten the mushroom get high too.
The Koryak shaman would bring prepared fly agarics to ceremonies in a sack, like Santa's bag of toys, and enter the yurt (portable circular domed dwelling) through the smoke hole (like a chimney).
Santa lives at the North Pole because for most Europeans, Siberia might as well be the North Pole. And in Europe today, Christmas cards still often depict the fly agaric.