Footprints on the Moon by Mark Haddon (illustrated by Christian Birmingham; Candlewick Press, 1996). I have not read many memoir picture books, but this one worked wonderfully. Best-selling author Mark Haddon writes of his own childhood studying the solar system and dreaming about the moon, then shows him tuned in the television, watching the first humans walk on the moon. He dreams he joins them.
It’s a lovely story, with soft illustrations that perfectly fit the dream-like quality to childhood. My 3-year-old son loved the little boy at the center of the story.