I don't know if non-fiction children's books count (I can't remember any showing up here), but I read a couple of delightful short books by Jean Fritz over the weekend called "Who's That Stepping on Plymouth Rock?" and "Shh! We're Writing the Constitution!" They're two of several children's books she wrote on early American history, light-hearted but historically accurate. (I already have a third one by her, which I bought a few years ago, about George III, entitled "Can't You Make Them Behave, King George?")
They're full of delightful information about such things as the top-secret nature of the Constitutional Convention (which had decided on the 18th century equivalent of a media black-out, and since Benjamin Franklin had a weakness for talk, the other delegates had to keep an eye on him at social gatherings and steer the conversation to safer topics if he seemed to be getting too close) or the comedy of errors at George III's coronation (somebody forgot the King and Queen's chairs at the coronation banquet, and the master of ceremonies decided to train his horse to ride into the hall up to the King's throne and then leave backwards - but he'd trained the horse too well, and it walked backwards all the way *towards* the throne, to its rider's dismay). The book on the Constitution even gives the complete text (minus the Amendments) at the back.