I found gold at the very surface, one. Just about four blocks beneath the grass. About four-five or...I've found a gold vein on the top of a hill in a small world before, though I didn't screenshot it for some reason. It was below a floating island, which probably explains it- that, or the terrain generation decided the hill itself was high enough to be a floating island.
Although, that's probably because the entire generation of that world seemed to be completely crapped.