The Seven Silly Eaters by Mary Ann Hoberman - This was a gift from a friend (you know who you are!), and since it was given to us we've read it every. single. day. Oldest absolutely loves it and almost has the whole thing memorized! So does Middlest, for that matter.
It's a story of seven children who will each only eat one thing and their poor, tired mother who makes them each their own meal everyday. I won't tell you what happens at the end, but suffice it to say, they all end up getting their way! It's wonderfully illustrated and fun to read aloud as well.
George and Martha Back in Town by James Marshall - We're new to the George and Martha series, and again, Oldest loves it. She asks to read it over and over again. Another one that's also fun for Mama. ;)
A Birthday for Frances by Russell Hoban - We currently have 5 Frances books checked out from the library right now. This is another series that both girls really enjoy. Frances is a little badger who sometimes has a hard time in life. I think these are great at teaching lessons without being too preachy or moralizing.