Need help finding beginner guitar songs for my father.

I'm an intermediate bassist and my father is basically a beginner guitarist (can't make an F.) I need some help finding some easier songs for him to play. Basically anything that uses G, C, D, Am, E, Em... the easier chords to play.
I've found a few country songs that he can play with a capo using G, C and D, or G, C and F, but I'm running out of places to look.
Here are some examples of the stuff we've been playing:

Dan Tyminski - Man of Constant Sorrow, Tiny Broken Heart, Sunny Side of the Mountain
CCR - Have You Ever Seen the Rain

Any upbeat Country, Folk or Classic Rock songs will help. I really love going to his house and playing, but the songs are getting stale. Any help is welcome. Thanks!

 

A great deal of those songs are in the genres I was looking for. Thanks a ton!