I have a fairly easy arrangement of Ashoken Farewell as a free download on my site. My Shenandoah arrangement is there, too:
https://dougyoungguitar.com/tabs
Pop songs often fit well in DADGAD for some reason, but tabs are harder to come by for many because of copyrights. I have a couple of Beatle tunes, and a few others. at Sheet Music Plus, the only way I can legally put them out. Links on that same page.
If you're not looking for fingerstyle instrumentals, but songs to sing while accompanying in DADGAD, it's not all that hard to just work out chords for any tune and play accompaniment in DADGAD. It tends to lend a different flavor to any song, which is kind of cool, as you get an instant "this is different" effect.