Paul Stamets, a well known and esteemed mycologist, answers the question of whether or not mushrooms should be eaten raw for nutritional or health benefits.
The crux of the answer is contained in the following quote but his article goes into more detail:
No, absolutely not! Raw mushrooms are largely indigestible because of their tough cell walls, mainly composed of chitin. Eating raw mushrooms can provide flavor, but not nutritional or health benefits. In some cases, eating raw mushrooms could be dangerous.