A pot bellied pig can and will eat vegetables and grains. They also enjoy apples and other types of fruit if you don't have any pig food. It is important to refrain from feeding them any type of junk food or foods high in refined sugars such as cookies and cakes.
Pigs eat anything. If you have scraps from cooking like carrot tops, lettuce stems and pea pods pigs love those. Don't feed them anything that has seasoning or added fats and sugars.
Pigs are omnivores, so you can feed them just about anything a human would eat. Table scraps including meat, fruit, vegetables, and breads should suffice to feed a pot-bellied pig.