I should've mentioned that I'm particularly interested in material not necessarily inherently directed at young children, although it's probable that little ones will like it.

Both "Sailor's Alphabet" and "Capital Ship" are in that category -- fairly sophisticated both verbally and musically. That's what I mean by "expanding his horizons" -- he gets enough kiddie material at pre-school!

I'm especially eager for traditional songs that have been printed as books. I just remembered, for example, that somewhere I have "Froggie Went a'Courtin'" in book form.