American music can trace it's roots from two distinctly American styles; blues and gospel music. I think that as Americans we should take time to familiarize our children with these two genres and their importance in the world of music. Charlotte Mason advocated teaching children folk music and this is the music of the folk of this country.
I am a big fan of early American country music which developed from gospel and was influenced by blues and the music of Irish and Welsh immigrants. I have found a wonderful set on youtube to teach specifically about this form of music. The set is comprised of clips from a BBC documentary, The History of Country Music. I recommend you look for this or borrow it from your library. It is excellent. If you would like to learn more about this style, check the links below.