Sometimes. It depends on the size, because dried beans can get pretty heavy.
Small homemade bean bags (the kind used for toys) can be filled with sand, beans, rice, wheat berries, or buckwheat hulls*, while larger bean bags (the kind used as chairs) are filled with much lighter materials, like packing peanuts, clean plastic bags, bubble wrap, and polyester fiber fill.
Commercial bean bags are commonly filled with polystyrene beads, although more ecologically sound fill options, such as shredded foam and buckwheat hulls*, are also available.
*Be warned: Stuffing your bean bag with beans, rice, wheat berries, and buckwheat hulls has the distinct disadvantage of making your hand-crafted bean bag a handy food storage device for insects, mice, and other pests.