Actually, Fly Agaric most likely won't kill you, unless you have an allergic reaction.
They are hallucinogenic more so than toxic.
Did you know that ancient Finnish herdsmen used to make a drink containing reindeer piss?
Reindeer eat the Fly Agaric fungi with no real affect to them. Their piss is mildly hallucinogenic after the fungi has passed through their system.
Ancient Finnish herdsmen must have had some weird evenings in their huts.

Probably explains a lot of Scandinavian folklore.
The question I want to ask is...........what was the first herdsman doing when he discovered this?