Thanks for that, Eve. I seem to recall Oscar Brand saying on one of his shows that he'd showed his daughter a (I think) C6 chord so she could do "Home On The Range" at school.

On his first album, Gordon Lightfoot had a song he wrote called "O Linda", recorded with just voice and bass. When I decided to do it myself, I sat down prepared to do extended battle with all sorts of weird jazz progressions ('cuz that's how it sounded), and discovered to my surprise (and relief) that the whole thing just riffed around an Em7 chord! There ARE one-chord songs out there, and damn good ones.