ny marksordiscolorations, 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,orthat are larger, may feature a hardened bottom stem that needs to be removed prior to slicingorpreparing it.
The name button tends to refer to a specific size, but they are not the only mushrooms that are A. bisporus. Portobello mushro