Folksong? Someone else's original tune?

[krummholz]

Attached is an extremely simple, 8-bar melody that is one of dozens of similar earworms that first started to infect me after watching Ken Burns's Civil War Documentary. They come into my head every once in a while and then leave; this one occurred to me recently after listening to a friend's string quartet movement, as it employs similar intervals in a way that to me suggests an American, perhaps Appalachian folksong. I've decided tentatively to use it to open a one-movement string quartet that will quickly become complex, contrapuntal, and troubled in the manner of Nielsen's 6th (or perhaps Brian's 31st) symphony. But I didn't want to waste too much time on it if the theme is actually by someone else.

At first I thought it was a variant of Jay Ungar's Ashokan Farewell, which is heard dozens of times in the Burns documentary, but I listened to the Ungar tune the other night and concluded that the connection is distant enough that it's not an issue - ditto the Shaker hymn Simple Gifts, which is if anything closer to it in character but still not nearly a match.

So, does anyone recognize this? I'm posting this in Composing instead of Name This Tune because I didn't want to post an audio file, and I think everyone here reads music. So...