Chris, even for CA and west-coast state's hunters, a gold coin is the holy-grail. And on the east coast, EVEN THE TOP NOTCH guys will rarely ever get a gold coin to their name.
You are on the right track to be studying the emigrant trail stuff. Because go-figure: When those easterners packed up their entire life to head this way on the "westward ho" gold rush times, they tended to consolidate all their wealth into weight/cargo-space sensitive loads. Eg.: instead of 500 large cents, they'd have a single $5, etc...... So whereas your relicky sites may not give up a lot of old coins, yet : When it DOES, they are often-time doozies.
There was several ways to CA : Around the horn by ship, or overland. And overland could be through the desert route (then heaven-help you if you got caught in the hot-summers). Or over the Sierras (heaven help you if you got caught in the winter snows). Or compromises like the Oregon route, which had slightly lower passes and elevations (yet added distance).
So you have lots of history at your finger tips ! Congratz on the gold coin.