Casey Henry teaches some backup for "Leather Britches" in the key of G. This version includes the C chord. Many versions are just two chords (G and D), so make sure you're playing the same version as the people you're playing with!
The lesson is taught entirely by ear--no tab. You can find many more lessons--all taught by ear!--on her website, as well as on the Murphy Method website.
'Shine On Harvest Moon' 40 min