Stonyfield Farm, also simply called Stonyfield, is an organic yogurt maker located in Londonderry, New Hampshire, USA. Stonyfield Farm was founded by Samuel Kaymen in 1983, on a 19th-century farmstead in Wilton, New Hampshire, as an organic farming school. The company makes the number-one selling brand of organic yogurt and number-three overall yogurt brand in the United States, according to Fortune magazine.