wee sing has books and recordings for kids music...
i also think i saw a recent thread about a kids book
about elizabeth cotten

good luck!

do you have the Rise up Singing book? there might be some good ideas there...people (and kids) rarely get the chance to sing rounds -0- that would be a great thing to introduce to them...

also if you see any good travelling musicians performing in your area, they might love the chance to do an assembly...if there is a budget...