Button mushrooms, or Agaricus bisporus, are small immature portobello mushrooms. They are white in color. Most button mushrooms are picked and sold when they are young, with their caps closed. The whole mushrooms is often used is recipes, stem included. To prepare button mushrooms, wipe them gently to remove dirt. They can be found in the wild, but can easily be confused with A. Californicus, a look-alike that is mildly toxic.
Mushrooms are the fleshy fruiting body of a fungus. They grow above ground, soil or from a food source. UV ray-treated (due to both sunlight and articial UV light tech) mushrooms are a source of vitamin d2. Many mushrooms are poisonous, resembling certain edible species. Gathering mushrooms in the wild is risky for the inexperienced and should only be undertaken by persons knowledgeable in mushroom identification.