Mushrooms are among the most mysterious life forms. The ancient Greeks believed they came from Zeus’s lightning because they appeared after rains and reproduced and grew.
    In the middle Ages, the circular patterns formed by some mushrooms were dubbed “fairy rings” and were thought to be the work of the “little people,” who danced around at midnight, performing magick rites.
    In the New World, some hallucinogenic mushrooms have been called “the food of the gods” and invested with supernatural powers. Much remains to be learned about fungi; some species contain dangerous toxins; many are not yet fully understood. Some mushrooms are of course edible.
    Economically valuable fungi include the strains of yeast responsible for the fermentation of grains and grapes in the beer and wine industries, and yeast responsible for the rise of baked breads; prized (and expensive) edible truffles, chanterelles, boletes and other delicious mushrooms; the ripening of Camembert, Roquefort and other blue cheeses; the source of the valuable antibiotic penicillin (from the bread and fruit mold Penicillium); and the source of ergotamine (from ergot fungus), a muscle and blood vessel and constrictor that relieves the horrible pain of migraines, stimulates uterine contraction during childbirth and prevents hemorrhaging.

What is a mushroom?
The mushroom is the fruiting body of a plant, the part of a fungus that typically appears above ground and contains its reproductive units or spores. Although mushrooms are usually considered members of the plant kingdom, they differ from most plants in that they lack chlorophyll and must rely on organic material for nutrition.

They do this in three ways: as saprophytes, as parasites, and as mycorrhizae.
1) Saprophytes live on dead organic matter, including dead wood, the dead tissue of living trees, dung, leaf litter, or conifer litter.

2) Parasites attack living plants or animals.

3) Mycorrhizae mushrooms have a symbiotic relationship with plants, usually either trees or shrubs. The mycorrhizal mushroom sheaths the end of the root of the flowering plant, expanding the plant's root system; the mushroom receives necessary carbohydrates from the tree.

Parts of a mushroom
Cap: The cap is the most conspicuous part of a mushroom and its shape can be important in identifying different genera. At first, many mushrooms caps are nearly round, conical, bell-shaped, or convex. As most species mature, the caps become broadly convex, flat or develop uplifted edges. Caps may be dry, moist, sticky, or slimy when they are fresh. A sticky or slimy cap may appear dry when it is old or dried out. In addition, to be wet or dry, cap surfaces may be smooth and hairless, powdery, granular, or adorned with radial lines, hairs, scales, or veil remnants.

Gills: are plate-like structures on the underside of the cap; they radiate out from the stalk and produce the spores. In many mushrooms, the gills run down the stalk slightly or deeply. In some, the gills pull away from the cap as it expands; these are referred to as seceding gills. Most gills have thin edges that may be minutely fringed, toothed, or colored differently from the rest of the gills.

Stalk: Most gilled mushrooms have a stalk, usually located at the center of the cap; some are off-center or attached at one side. In a few cases where the stalk is absent, the mushroom usually grows on wood. The stalk surface may be smooth, dotted, lined, netted, scaly, powdery, or hairy. Stalks may be hollow, solid or filled with cottony tissue. Many species have a ring, a skirt or band-like tissue, or a zone of fibers on the stalk left by the partial veil as the mushroom expands.

Veils: Some mushrooms have veils, membranes that cover and protect either the entire immature mushroom or the immature gills. As the mushroom enlarges, the membrane ruptures, usually leaving traces on the cap or stalk. A membrane that encloses the immature gills on the unexpanded cap is called a partial veil.

All mushrooms produce millions of spores that are dispersed in various ways.

    How to make a spore print: A spore print is essential for accurate identification of many mushrooms. To make one, cut off the mushroom’s stalk close to the base. Place the cap with the gills or pores facing down, on a piece of white paper. If you are in the filed, enclose the cap and paper in wax paper and place them on the bottom of a basket. At home cover them with a glass. Sometimes the spores fall more readily if you place a drop of water on the cap before you cover it. Some mushrooms produce spore prints in a few hours; others take much longer, sometimes over-night.

    After you have located the picture of the species most like your specimen, check the field characteristics listed in the text description, and the spore print color. Also, check the look-alike's section, and eliminate each, item by item. If you plan to eat the mushrooms you have found, make sure that the edibility section and the comments describe them as safe. Mushroom hunters who have microscopes can gain extra assurance that their identification is correct if they examine the spores microscopically. If any doubt remains about the edibility of a species, do not eat it.

Site: National Audubon Society A Field Guide to Mushrooms

    Mushrooms are low in carbohydrates, calories, and sodium and are cholesterol and fat-free!  They are high in riboflavin and contain as much fiber as 1 medium tomato.  They are also a good source of niacin, pantothenate, and copper.

While medicinal mushrooms have been used in China and Japan for more than 3,000 years to boost immunity and fight diseases such as cancer, only in the last decade has their power begun to be recognized in the United States.  In more scientific terms, a number of compounds in fungi have been found to stimulate the function of the immune system, inhibit tumor growth and boost intestinal flora.  Particularly, mushroom substances called terpenoids help kill bacteria and viruses and exert anti-inflammatory effects, while complex chain-like sugars called polysaccharides have been shown to exert antitumor and immuno-stimulating properties.