Dave, here is a quote from Paul Stamets’ book “Mycelium Running”:
“Mushrooms are rich in protein, very low in simple carbohydrates, rich in high molecular weight complex carbohydrates (polysaccharides), high in antioxidants, and very low in fat. They lack cholesterol, vitamin A, and vitamin C. They are a good source of some B vitamins…as well as ergosterols…They’re high in dietary fiber…”
He provides charts for nutritional value for a bunch of popular edible mushrooms.
However, even if they had no value, they sure do taste good. And I’d still eat them! As I’m sure you would, Dave.