White Amanitas are lethal, never touch those, but with Muscaria you could have some fun.

These are my favorites because of their common name. Destroying Angel.

Fun fact: the survival rate without treatment is about half, but that goes up to ~90% if you get treated quickly. However, it can still destroy your liver. The toxin is thermostable so cooking doesn't break it down. It is excreted in urine so a lot of the treatment consists of pumping you full of fluids and making you pee a lot. There is no actual antidote to the toxin.