@The Pentacle Queen,
i'm not a parent, but as a life-long avid reader, i've always taken an interest in the books that the children of my friends are given to read in their early development. i've always made a point of making gifts of three books that had an early impact on me as a young child: The Story of Ferdinand
by Munro Leaf, The Pokey Little Puppy
by Janette Sebring Lowry, and Corduroy
by Don Freeman.
In the last few years, I added Zen Shorts
(by Jon J. Muth) to the list of books i like to give. As much as i like Zen, myself, i was mostly drawn to it because i thought that the beautiful watercolor illustrations would appeal to little kids.
Of course, i understand that i might be undershooting the age range that you're aiming for in your writing. If you are targeting seven-year-olds to, say, nine, then i suggest Sideways Stories from Wayside School
by Louis Sachar
From ten-up, Judy Bloom, Susan Cooper, and (again) Louis Sachar all wrote pretty good pre-tween books or series that strike the chords of important human values.
i hope this was helpful, but i expect that i haven't named any esoteric titles.