Raisins. Dried seedless grapes, raisins are a common snack food or used in cereals, cookies, and puddings. They are fairly high in iron, with one cup of raisins containing nearly 6 mg. Raisins are also rich in potassium, calcium, magnesium, and phosphorus, and have traces of copper, zinc, and manganese. They have fair amounts of the B vitamins and are often helpful in providing quick energy.