If you fly high above the Lumpy Pumpkin and then hop off your Loftwing, these rainbow-colored... bugs, I guess, start falling with you. If you move around from side to side and collect them all (I couldn't count them, but there are about ten or so) then you'll get rupees! I think I got 20 Rupees, but it might be dependent on which color bug you pick up last? Maybe? I dunno.
I've never heard anyone mention this before. Has everyone been holding out on me or something? Have you found any other secrets?