The easiest way to grow mushrooms at home is with a five gallon bucket full of coffee grounds, and some Oyster Mushroom spawn. Spent coffee grounds can almost always be obtained free from a nearby coffee shop. Oyster mushroom spawn can be purchased online from Amazon or from a mushroom lab near you. Detailed instructions for putting together a five gallon mushroom farm can be found http://www.stormthecastle.com/terrarium/how-to-grow-mushrooms.htm
Grow Your Own Mushrooms in Used Coffee Grounds - Alejandro Velez and Nikhil Arora, co-founders of Back to the Roots LLC in Oakland, Calif., have grown a business out of other companies' trash. They manufacture grow-at-home oyster mushroom kits filled with used coffee grounds. WSJ's Lauren Rudser reports.