Forgive me if I take this from the sublime to the ridiculous, but the "Achey Breaky" is a 2-chord, same pattern as "Jambalaya". Mind you, I've only done it with the "Weird Al" lyrics ("You can torture me, with Donny and Marie...").

By way of attempting to redeem that, I do believe that Woody's "Pastures of Plenty" is a 2-chorder. Bm and D, methinks.