Black walnuts are native to Iowa. The trees are best known for their high value as lumber. The nuts are difficult to shell making retail sales an unlikely market, though grafted trees will provide the best odds of success. There is a wholesale market for walnuts as seed. Some processors will purchase walnuts for their meats as well as the dye that can be made from the shells, used by crafts people. There is a growing awareness of black walnut for oil and medicinal products.