I don't see a discussion topic of compiled information, so I'm going to share this find:

Three-star Lottery:
1st) Gold Bottlecap
2nd) Bottlecap

I haven't been assed to write down the other prizes as they're usually shit. Also, the Two Star lottery's first place prize is a big nugget IIRC.

You can also get regular bottlecaps from the Two Star Ghost House. (Both as extra drops and the "main" prize.)