Mycology

I figured I'd ask you guys since you know about or at least like mushrooms. I heard Paul Stamets say they are equivalent to smoking cigarettes that's how toxic they are to the human body. Now I'm not just believing him instantly because he's some expert on mushrooms. I am researching and gathering data. Are they toxic for consumption, are they as bad as he says, and are if so are the less mature stage (white button mushroom) free from these toxins?

Also bonus question can mushrooms spread their fungus inside your body and dwell for weeks in your body? That question is out there but mushrooms are super good at spreading.