[TOMT] Help me identify this simple guitar riff! Recording inside! (SONG)

I recently started learning guitar, and today I was playing around and played a very simple progression that I'm positive is the base for a very popular (or at least well-known to me) acoustic song.

If it helps, I'm 19 and I generally listen to alternative/indie/folk. I initially thought it might be from a Switchfoot or Relient K song, but no dice on those so far.

I'm playing a D chord and simply moving up and down the frets while plucking the D and G strings. I also have a Capo on the 2nd fret. It's the least fancy thing in existence, but it's so familiar to me that it's driving me insane.

I very sloppily recorded it quickly so you can give it a listen.

https://soundcloud.com/forgetandslowdown/mystery-guitar-riff

Any help would be appreciated, thanks!