White mushrooms, like all mushrooms, grow from microscopic spores, not seeds. Plants growing from spores are called fungi. A mature mushroom will drop as many as 16 billion spores. Spores must be collected in the sterile environment of a laboratory and then used to inoculate pre-stabilized grains or seeds to produce a product called spawn (the mushroom farmer's equivalent of seed).

Because mushrooms have no chlorophyll, they must get all their nutrients from organic matter in their growing medium. The medium, called compost, is scientifically formulated of various materials such as straw, corn cobs, cotton seed and cocoa seed hulls, gypsum and nitrogen supplements. Preparing the compost takes one to two weeks. Then it's pasteurized and placed in large trays or beds. Next, the spawn is worked into the compost and the growing takes place in specially constructed houses, where the farmers can regulate the crucial aspects of humidity, temperature, CO2/o2 gases, waterings and hygienic conditions.

In two weeks, the compost becomes filled with the root structure of the mushroom, a network of lacy white filaments called mycelium. At that point, a layer of pasteurized peat moss is spread over the compost. The temperature of the compost and the humidity of the room must be carefully controlled in order for the mycelium to develop fully. Eventually, tiny white protrusions form on the mycelium and push up through the peat moss. Farmers call this pinning.

The pins continue to grow, becoming the mushroom caps, which are actually the fruit of the plant, just as a tomato is the fruit of a tomato plant. It takes 17 days to produce mature mushrooms after the peat moss is applied. Size is no indication of maturity in mushrooms. Perfectly ripe ones vary from small buttons to large caps.

Each crop is harvested over a period of several weeks and then the house is emptied and steam-sterilized before the process begins again. The remaining compost is recycled for potting soil. The harvested mushrooms are set in carts, refrigerated and then packaged and shipped quickly to supermarkets, food processors and restaurants. The entire process from the time the farmer starts preparing the compost until the mushrooms are harvested and shipped to market takes about two to three months.