Photo: cyclonebill on Flickr
Air-popped popcorn is low in calories and contains levels of potassium, phosphorous, calcium and magnesium (good for bone-building). As with other treats, keep it simple: feed only plain popcorn to your dog. Additives like flavoring, butter, and salt are not helpful!
The next one is a veggie, but most dogs love 'em, which is good, because they're great: