Genuine gold coins from the Oregon Exchange Company are basically priceless for most of us normal folks. The catalogs report $30,000 to $300,000. If you have a genuine piece, it is certainly a magnificent treasure. Almost 100 percent of the pieces you find are replicas, worth zero.
DO NOT CLEAN YOUR COIN. CLEANING RUINS VALUE.
The catalog values above come from The Red Book, 'A Guide Book of United States Coins' by R. S. Yeoman. The only decent pictures of a genuine coin (that I can find) are from the Smithsonian, found on Flickr at this link, and at this one for the other side. Acknowledging the Smithsonian as the source, we have small versions of those images here: