For young piggies you want to feed them alfalfa hay for the extra nutrients it has, and make sure their pellets have vitamin C as Guinea pigs cannot make their own and need this in their diet. Other then that I'm sure you've got household veggies they would love but I suggest heading over to the food section of this forum to find out what's poisonous to your pigs. For example Guinea pigs can eat tomato, but the green top of the tomato is toxic to them.