You will find legends about dogs from many traditions which would be perfect for a Storybook project.
Research Tip: For dogs in mythology, Wikipedia has a List of Mythological Dogs, and there is also an article on Cultural Depictions of Dogs. For dogs in folklore, you can do a search for dog at the UnTextbook, and that will take you to lots of different kinds of stories; and you can also search for dog in the story titles at the Freebookapalooza. There are also lots of Aesop's fables about dogs.
Past Projects: