Walnuts are the oldest tree food known to man, dating back to 7000 B.C. The English Walnut and the Black Walnut are the two most common varieties of walnuts grown for their seeds. The English Walnut (Juglans regia or Jupiter’s royal acorn) originated in Persia, where it was reserved for royalty and the Black Walnut (Juglans nigra) is native to eastern North America. The North American walnuts were first cultivated in California by the Franciscan Fathers in the late 1700s. By the 1870s modern walnut production had begun with orchard plantings in southern Santa Barbara County, California.

The United States is the world's largest exporter of walnut seeds. Walnut seeds are a high density source of nutrients, particularly proteins and essential fatty acids. They are enclosed in a green, leathery, fleshy inedible husk. Once removed, the husk reveals the wrinkly walnut shell, which is in two halves. This shell is hard and encloses the kernel, which is also made up of two halves separated by a partition. The seed kernels are available as shelled or roasted. "Walnuts rank above peanuts, almonds, pecans, pistachios and other nuts," said Joe Vinson, Ph.D., who did the analysis. "A handful of walnuts contains almost twice as much antioxidants as an equivalent amount of any other commonly consumed nut. Enjoy the flavorful and crunchy health benefits of walnuts!