You have canine teeth for eating meat instead of tree fruits. Your body can also extract nutrients from this fungus versus merely passing it like if you ate some wood or something else entirely non-nutritious. You might be one of those people who are able to process lactose effectively. None of these things are unnatural to our species if we have natural mutations in our population that confer these adaptions.

Except psilocybin-containing mushrooms are edible, death caps are not.