You can put all kinds of food scraps into a composter, such as apple cores, banana peels, vegetable skins, coffee grounds, eggshells, and bread. However, animal products, such as meat, dairy, and bones, generally aren't recommended for composting because they can harbor pathogens and attract pests. You also can add grass clippings, leaves, wood shavings, hay, animal manure, and other yard waste, as well as paper towels, cardboard, and shredded newspaper. Things you generally shouldn't put in a composter include oils, pet waste, diseased plants, charcoal, and ash.