Hi, Pappy -
While gold wasn't discovered in California until 1848, the land certainly made some people rich. The Spanish land grants (ranchos) were huge parcels of land, and they must have made their owners wealthy. Some of these land grants still exist, most notably Tejon Ranch on the Grapevine (Interstate 5 between Bakersfield and LA).

https://ranchingheritage.org/ranch-highlight-ranchos-of-alta-california/.

Historic Ranchos of Los Angeles: https://curtiswrightmaps.com/product/the-historic-ranchos-of-los-angeles/ - note the Rancho names that have remained as modern placenames.