I've just noticed there is some music by Ruth Crawford Seeger (Pete and Mike's mum) on YouTube. Like this:

Prelude no. 2

which I think is the most difficult piece to follow from the score that I have ever seen.

Very, very un-folky. Probably the most hard-edged, uncompromising art music that anybody was writing in the US at the time. It was a great loss that she stopped composing.