Please see the main article on Amanita muscaria, and how it is edible if parboiled for an introduction to the edibility of Amanita muscaria.
Please download, read, and share my article on the edibility of Amanita muscaria co-authored with David Arora and published in the peer review journal Economic Botany in 2008:
As the article explains, Amanita muscaria is not poisonous in the sense it can kill you. It is poisonous in the sense that if not parboiled in plentiful water (the “toxins” are water soluble), then raw or undercooked mushrooms eaten (in moderation) will cause you to become inebriated and possibly nauseous.
Becoming sick to ones stomach is the most common meaning to “poisonous” in mushroom field guides although one must always remember that there are mushrooms that are poisonous in the absolute sense that dinner-sized portions can either kill you or cause serious organ damage. But Amanita muscaria is not poisonous in that sense.