My dad used to sing "The Old Chisholm Trail" and, since he only knew 2 or 3 "official" verses, would make up a dozen or so more about my brother and me each time he sang it. Very creative.

I like the one I found either in these archives or over in the COWPIE archives about "The Cowboy's Faith (No Horses in Heaven)".

There's one with a pretty melody called "Hills of Mexico" about a young man from Arkansas who is lured away to work in Mexico as a ranch hand and returns only to find everyone he knew is gone. Can't find the lyrics.