Heartnuts are a cultivar of the Japanese walnut. They open into two flat heart-shaped halves, like a locket. Nuts are high on the diet culture list of good-for-you foods, and heartnuts have been shown to be a particularly healthy nut _ high in fiber, antioxidants, and protein. The taste is sweet, mild and pleasing. A wonderful nut for cooking and baking, it is especially flavorful toasted.