I'm listening through to see if I can find something that fits that description.
I would recommend checking out those websites out there that have free downloads of old 78's. They started churning out those around the 1890s. Since I'm not at all too sure what you are looking for... I've found quite a bit of happy-pre-war-jazz I could point you too.
Or, to let you do your own happy hunting...
Here's a good source:
http://cdbpdx.com/78records/
Username: New090908
Password: 654321
With five different renditions of Hallelujhuah I'm a Bum... this source is well worth a look at. They also have five versions of The Bum Song. They've also got The Dying Hobo, Hobo Bill's Last Ride, and Wild and Reckless Hobo on there. Lots of hoboes. Hoorah.
There's more at
http://78records.cdbpdx.com/
They're all free for downloading. It's a lot of hit and miss. I've gotten some pretty hilarious tunes from there, though, and some great diddies that are fun to muck about to.
1920s Ukrainian makes me grin.
A song that makes me think of a combination of happy jazz + rural country
might be Kentucky Home by The Happy Six. The Salty Dog Rag is always gold! One of my favourites to dance to.
Lil Liza Jane by Earl Fullers Famous Jazz Band is also worth a listen to. It's jazzy, but still has the 'bouts of unison singing to this old time tune. Nickety Nackets Now Now isn't quite jazzy, but it is "hill billy-esque." Red Headed Music Maker with Wendall is bluesyish on the uke...
If you've got any examples of what you're looking for, that might help me understand more exactly what kind of sound you're looking for.