Mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source.mushrooms are consumed for their nutritional and culinary value. Mushrooms, especially dried shiitake, are sources of umami flavor from guanylate.All types of edible mushrooms contain varying degrees of protein and fibre. They also contain B vitamins as well as a powerful antioxidant called selenium, which helps to support the immune system and prevent damage to cells and tissues.