Not specifically for shapes, but you might check out some of the "I Spy" books. They are fantastic for teaching recognition of things. My daughter LOVED them at that age (and before actually). In addition to being fun, it is a wonderful way to expand your child's knowledge of the world around you. Often with pictures of things you might not typically encounter in your day to day routine. We "found" all the letters of the alphabet, numbers, dogs, keys, trumpets, lighthouses ("what's a lighthouse, Mommy? What does it look like?"), etc.
There are lots of different I Spy books, and they are ALL kid friendly... nothing provocative or questionable in them. Enjoy!
One of her favorites was "I Spy: Schooldays"
http://www.scholastic.com/ispy/books/index.htm