You can buy whole, dried cordyceps in health food stores and add them to soups and stews, or drink tea made from powdered cordyceps. You can also get cordyceps in capsule form. To treat general weakness, take cordyceps once a day, following the dosage advice on the product. For health maintenance, take it once or twice a week. You should be able to find it dried or fresh in Japanese markets, gourmet foods stores, or upscale supermarkets.
Research indicates that maitake has anticancer, antiviral, and immune-system enhancing effects.
It may also reduce blood pressure and blood sugar. Like maitake and other related mushrooms species, reishi can improve immune function and inhibit the growth of some malignant tumors. It also shows significant anti-inflammatory effects, reduces allergic responsiveness, and protects the liver. You can buy dried, ground mushrooms and use them to make tea if you don't mind the bitterness. Otherwise, I suggest buying reishi tablets or capsules, which are available in health food stores.