Mushrooms and truffles are relatives of each other in the fungus kingdom. Both are highly prized ingredients for food recipes, although truffles, due to their rarity, are much more so. Although mushrooms are more prevalent, they are complementary ingredients to dishes due to their variety in shape and flavors. Although both are from the fungus family, there are a number of differences between mushrooms and truffles, ranging from where and how they are located to how much they cost to how they are used in various recipes.
Most mushrooms sold in the U.S. are grown commercially. The most popular is the button or "foodservice" that are cream colored and typically sold in 8-oz. packages. Other popular mushrooms in the U.S. are the portobello mushroom, which is a large, brown mushroom with black ribs and a woody, almost nutty flavor. They are related to the button mushroom -- in fact they are just an older version of a button mushroom. The cremini mushroom is the in-between stage between a button and a portobello mushroom. As such, the cremini has a stronger flavor than a button mushroom, but is milder than a portobello mushroom. Other mushroom varieties include oyster, morel, chanterelle, shiitake, enoki and porcini. All have different flavor profiles and are used in different styles of cooking. As far as truffles go, there are generally two kinds -- white and black. Truffles are known for their earthy, garlicky flavor. They are divided up into winter and summer varieties, based on when they are harvested. The winter black truffle has the most robust flavor of all the truffles.
Although most U.S. mushrooms are grown commercially on farms, you can find them just about anywhere. They grow on just about anything; for example, button mushrooms typically are found growing on dried horse manure. They are also commonly found in thick woodsy settings, growing out of old tree stumps and fallen logs. You should not eat raw mushrooms found in the wild unless you are an expert on them. Some mushrooms have hallucinogenic properties (and are sold in the illicit drug trade as "magic mushrooms") and some can even be fatal when ingested. Truffles have no such risks. However, truffles are extremely difficult to find due to the fact that they grow beneath the ground with nothing growing above ground to signal their presence. In previous centuries, pigs were successfully trained to find truffles due to the pungent aroma truffles give. Whereas mushrooms can be found and grown anywhere, truffles thrive only in certain climates. They mainly grow in France, Italy and Croatia in Europe and parts of North Africa. Truffles have been unearthed in the Pacific Northwest states of Washington and Oregon, due to the moist climate found there.
Due to their popularity and availability, mushrooms generally are not that expensive. It's not unusual to be able to buy a pound of button mushrooms for $2 a pound (as of July, 2011). The more exotic the mushroom, the higher the cost per pound. Portabello mushrooms typically cost more than twice as much as button mushrooms and the harder-to-find mushrooms, such as enoki and chanterelle, are somewhat higher than that. Truffles, on the other hand, are cost prohibitive, known to be worth their weight in gold. The most expensive truffles, either the black perigord truffle or the white alba truffle, have been known to sell for as much as $250 per ounce.
Mushrooms are very versatile and can be eaten raw, such as in salads; baked, as on a pizza or stuffed with crab filling; or sauteed and added to sauces such as marinara sauce or grains such as risotto. They also make hearty soups and excellent substitutions for meat in vegetarian dishes (some portobello mushroom caps have been used in place of steak in some vegetarian dishes). Truffles have less functionality in recipes but are no less prized for their flavor. Due to the potency that a raw truffle has, it is generally served either shaved or minced on top of an entree to complement the dish's flavor. Truffles are sometime used as a component in pate de foie gras. They are often used in egg dishes, such as scrambled eggs. To make the truffle go farther, they are often used to make truffle oil, which is used in salad and sautes.