After taking California, the U.S. needed a way to sort through land claims and established a Public Land Commission. This operated from 1852 to 1856, principally in San Francisco but also briefly in Los Angeles, taking depositions and issuing decisions. Records of the 813 claims it heard (and the lawsuits that ensued) survived the 1906 fire.
The documentation is not sparse, but I haven't been able to answer one question: in which building or buildings in San Francisco did the Commission meet?