Keystone Mushroom Farms, Inc. was a producer, canner, and distributer of mushrooms in Coatesville, Chester County, Pennsylvania. It was the successor of two previous businesses, L.F. Lambert Spawn Co. and Keystone Mushroom Company, Inc., which were formed in the early 1920s with complementary functions of spawn research; production and sales; and mushroom propagation, canning, and distribution. These records document the L.F. Lambert Spawn Co. and the Keystone Mushroom Company, Inc. The collection includes financial records, correspondence, payroll, reports, and shipment and inventory information. Of special interest are the records documenting Lambert's work with the War Production Board to produce penicillin.

More than half of the mushrooms in the United States are grown in and around the town of Kennett Square, Pennsylvania, which calls itself the "mushroom capital of the world." Walter W. Maule (1892-1964) and Charles C. Brosius (1930-), both Chester County, Pennsylvania, mushroom growers, were active in professional trade associations and advocates for their industry. This small collection on the mushroom industry consists of papers that document mushroom industry educational courses and professional trade associations. The collection provides insight into the role profession trade associations such as the Mushroom Growers Cooperative Association, the Mushroom Cooperative Canning Association, and the American Mushroom Insitute agriculturual play in affecting legislation and mushroom farming practices.

Over half the mushrooms in the United States are grown in and around the town of Kennett Square, Pennsylvania, which proudly calls itself the mushroom capital of the world. This oral history collection brings together interviews with individuals whose experiences capture the many different kinds of work and knowledge involved in mushroom cultivation, harvesting, packing, distribution, and marketing, and how those processes have changed over time.