Last week we borrowed The m&m's brand chocolate candies Counting Book by Barbara Barbieri McGrath from the library. C and R had a lot of fun with this book.
You only need 12 m&m's, but you do need specific colors so plan ahead if you want to avoid dumping more candies than necessary for your child. I did not plan ahead and C and R had too many m&m's in front of them, but I was able to remove the leftovers without any complaint once I told them they could each have 12 at the end of the book.
The book teaches the numbers 1 through 12 and simple math like addition and sets of 12. The directions were simple enough for R (3) to follow.