Regarding the nutritional value of mushrooms, a few counterpoints. Firstly, you are only looking at a single variety of mushroom (cremini). Second, 7% manganes

Regarding the nutritional value of mushrooms, a few counterpoints. Firstly, you are only looking at a single variety of mushroom (cremini). Second, 7% manganese, 17% phosphorus, 15% potassium, and 12% zinc per 3.5oz serving representing 22 calories (or ~1/100 of your daily caloric intake) is nothing to sneeze at. Go check out 100g servings of various other veggies to get a baseline. It is also likely that these nutrients are far more bioavailable in mushrooms than they are in, for instance, brassica veggies, due to lack of phytates and other uptake inhibiting molecules (so called "anti-nutrients"). FYI, 3.5oz of mushrooms will cook down into less than 1/4 cup, so if you desire, you can eat substantially more than this incorporated into a dish without it necessarily overpowering flavor or texture. Finally, mushrooms are chock full of other hugely beneficial (but under-studied) dietary compounds such as beta-glycans, triterpenoids, ergosterol, and all manner of immune-modulating tryptophan metabolites such as indole-3-proprionic acid.