Button Mushrooms

Agaricus bisporus is usually called the common or commercial mushroom. These fungi are available at many grocery stores, and have a white cap. The species may be sold under many different names, some of which refer to its size. Small white versions of A. bisporus are generally referred to as button mushrooms, while larger versions may be given a more generic name.

True button mushrooms are picked when they are very young and when the caps of the mushroom are still closed. They should be free of any marks or discolorations, and the stems on their bottoms should not have hardened. Generally, when a cook buys fresher mushrooms, they are easy to slice and the whole mushroom, stem included, can be used. Those that have sat for a few days in the grocery store, or that are larger, may feature a hardened bottom stem that needs to be removed prior to slicing or preparing it.


The name "button" tends to refer to a specific size, but they are not the only mushrooms that are A. bisporus. Portobello mushrooms are large, brown versions, for example, as are smaller Italian brown mushrooms. Consumers might also find wild mushrooms in button size, simply meaning that they’re smaller and picked at an earlier stage.