Here's an example. A buddy (Greg, who plays banjo on this one) sent me this recording. The tune is an obscure one: I Love That Girl. Nobody in the group knew the tune, led by fiddler Bill Galloway from Arkansas. But listen and you can hear how everyone picked up on it. By the end, they were playing it like they've known it for years.
I love that aspect of this genre. Simple tunes, easily learned. You don't have to know 'em to play 'em!