1907, Mark Twain, Chapters from My Autobiography, ch. 26:
On the Saturday holidays in summer-time we used to borrow skiffs whose owners were not present and go down the river three miles to the cave hollow (Missourian for "valley"), and there we staked out claims and pretended to dig gold, panning out half a dollar a day at first.
His father came out in '49 with the gold rush crowd, panned out a good pile, and then, liking the life—San Francisco was a gay little burg those days—opened one of the crack gambling houses down on the Old Plaza.