Thanks for the clarification Bob.
Actually, that's a common food myth about mushrooms not having food value. Mushrooms (I'm talking the common white-button sort here) are a good source of Niacin, Riboflavin, Folate, Phosphorus, Iron, Panthothenic Acid, Zinc, Potassium, Copper, Magnesium, Vitamin B6, Selenium and Thiamin. Mushrooms actually have more potassium than a banana which is really a good thing when you are doing intense activities where dehydration and electrolyte issues can arise. Mushrooms, all varieties, are also a good source of protein. Oh... and they are the only vegetable source of Vitamin D with 100 g of white mushrooms having 4% of the RDA and shiitake having 13% of the RDA for Vitamin D.
I think I know just a little too much about food... lol. Occupational hazard?
I'd go for crimini or shiitake.
Edited to add... they also have fibre and they rehydrate well.