For general cooking, the mushrooms I use are small white mushrooms—often called button mushrooms because of their size, that of a suit button. They are always left whole in recipes. Some supermarkets package button mushrooms, but many don’t. When button mushrooms are not available, larger white mushrooms can be cut in half or quartered to approximate their size. There are a number of other mushrooms now easily found in supermarkets: portobellos, cremini (which are small portobellos), and shiitake. These all have more flavor than white mushrooms and though they are not found in traditional French food, don’t let that stop you from trying them.