Chinese and Japanese gardeners have been growing mushrooms for more than 1,000 years. There are about 14,000 species of mushrooms, but only about 250 are edible. If you’re looking for a side-hustle moneymaker, fresh gourmet mushrooms are definitely a high-value crop. Read on for a quick guide to mushrooms, including a rundown on the easiest species to grow at home: white buttons, oysters, portabellos and wine caps.