According to the U.S. Department of Agriculture, Americans eat about 130 pounds (59 kilograms) of potatoes each year [source: U.S. Department of Agriculture]. It's no surprise that many people enjoy potatoes on Thanksgiving Day as well as throughout the year. Mashed potatoes are usually used as a side, but when reusing leftovers, you can camouflage those mashed potatoes by incorporating them into a main entrée. Check out this recipe for Shepherd's Pie. Just substitute your leftovers for the instant mashed potatoes in the recipe.