While they are not vegetables, mushrooms are cooked and eaten as such. Mushrooms develop without chlorophyll, unlike other plants that are unable to grow without air or light. Mushrooms develop according to climatic conditions: They need cool temperatures and moisture. They can emerge in a few hours after rain, hence the idiom « to spring up like mushrooms ». Mushrooms give the lie to the cliché « everything natural is good »: Many are actually deadly because they contain lethal toxins.

Mushrooms can be found throughout the year, not counting cultivated varieties, such as shiitake, oyster mushrooms, and button mushrooms. Fresh mushrooms are more often sold loose by weight. They can also be packaged in trays. You should be aware of their origin, because the best are always those picked in the vicinity. Many are actually imported and stored in cold storage. Mushrooms should never be slimy or contain worms. They should have a clean, uniform color, and give off a pleasant smell. The smallest are always the best. Some mushrooms can also be bought frozen, often as a mixture of varieties and always ready to use. Dried porcini (ceps), morels, chanterelles, horns of plenty, oyster mushrooms, and shiitake are also available, alone or mixed, in bags. Button mushrooms, porcini, golden chanterelles, morels, and truffles can also be found preserved in cans or jars.

Mushrooms need to be washed only when they are covered in a great deal of soil. Washing should be quick, otherwise they will soak up the water. The earthy stem (stalk) should always be removed. Then they should be carefully dried. Cleaning with a brush is most often enough.

Mushrooms are most commonly pan-fried.

Mushrooms can be prepared as dishes, or as a garnish for meats, poultry, fish, or eggs. They can be combined with other vegetables, patés, and cereals, and can also be stuffed. They are given infinite uses in the cuisine of France and other countries.

Fresh mushrooms can keep for two or three days in the refrigerator or cold room, preferably spread out over a tray, but never crammed together in a plastic bag. Frozen mushrooms should be put straight in the freezer without breaking the cold chain. Dried mushrooms should be stored in a container in a dry place. Cans or jars can be stored at room temperature if unopened.

Mushrooms are low in calories, and, except for truffles, are never eaten plain. They are more often cooked in or dressed with a fat or oil, which modifies their nutritional value. The long-held notion that mushrooms are “plant meat” is absolutely false. Even if they do contain a little protein (average 2 percent), this does not justify the name. This comparison probably comes from the particular texture of mushrooms, which is quite dense, and also from their high fiber content, which adds to the feeling they give of being full, especially if cooked with garlic and butter. Most mushrooms contain minerals and the B-group vitamins. Some, like golden chanterelles, also contain carotenes.

There are countless varieties of mushrooms. More than 2,500 varieties of wild and cultivated mushrooms have been recorded, although few varieties are, in fact, both edible (a large number of mushrooms are poisonous) and taste good. There are three main categories of mushrooms among those commonly eaten in Europe: Gilled mushrooms or agarics, including amanita, parasol mushroom (or lepiota), amethyst deceiver, saffron milk cap, fairy ring mushroom, St. George's mushroom, oyster mushroom, agaricus (to which button mushrooms belong), and the portobello (field) or meadow mushroom. Boletes, including different varieties of boletus, particularly porcini. Chanterelles, including golden chanterelle, sweet tooth or hedgehog mushroom, horn of plenty. The shiitake, morel, and truffle belong to other species. Certain species grow abundantly in fall (autumn), but others are picked in spring, summer, or in winter (e.g., truffle).