I don't have any advice as to where to find complete songs. But since you're playing acoustic guitar you should check out Lisa McCormick's fingerpicking series. Its like twice the bang for your practice buck, because you're learning new chords but also learning how to finger pick as well... you'll find that you get a lot of "wow that sounds cool" factor for the effort you put in.

Because you are new, when you check out her series, make sure you know at least one chord first, and can play it without any buzzing or dead notes. So for instance, if she says "this song has the chords Am, C, G..." start with the Am chord, make sure you can play it, then learn the fingerpicking pattern. Then learn the rest of the chords, again, just so you can strum them cleanly. Finally, go through the chord changes with the fingerpicking pattern VERY SLOWLY, as slow as you need to so that you don't make mistakes.

Remember, you can take a break from learning the chords & changes and focus just on the fingerpicking pattern. She'll have you sounding like a pro in no time!

Good luck!