The Granny Square Book by Margaret Hubert.
After making about 10 of the blocks in The Granny Square Book (Kindle Edition), I'm in love. Making squares patterns that have charts is totally the best. The charts are a little on the small side, but I don't have any trouble reading them. It is super easy to notate any changes, and the Kindle keeps track of my last place. For the Frances Flower pattern, I substituted a round of hdc for the last two rounds (of sc) in the pattern. The rest of these four were made with no stitch substitutions.