what was the relationship of mexico and spain with california during the time of the gold rush?

Answer 1

California was Spanish from the 1760s until into the 1820s (and unofficially into 1830) when Mexican authority took hold. The Mexican leadership lasted only until the influx of Americans, resulting from the discovery of gold in January 1848, reached massive volume and political clout. In 1850 Mexico lost California to the United States, and the territory became the thirty-first state to join the Union.
I've included an excellent resource from the University of California press, Children of Coyote, Missionaries of Saint Francis Indian-Spanish Relations in Colonial California, 1769-1850 by S. Hackel, which addresses the turbulent change in the state. I hope this information is helpful.

Answer 2

Spain was already out of it. California was independent from Mexico, but not part of the United States yet.