Tom, I checked "Marriage Records of Shasta County California 1852-1904" compiled by the Shasta County Genealogical Society in 1973 and there is no listing for the marriage you seek.Upon further research, I think I know why.
Cottage Grove is not in Shasta County.It is presently in Siskiyou County.In 1862 it was in Klamath County, Calif., a county which has been defunct since 1874.In a book by Owen C. Coy which was published in 1919, at that time the majority of Klamath County records had been stored in Humboldt County.Who knows what has become of them since.
Check out the excellent information about Klamath County on this website:
The information about the marriage records looks like there were only 3 marriages recorded during the time period you need.This is bad news.In addition, white men sometimes had difficulty finding someone who would marry them to an Indian wife.There was a provision in both California and Oregon law, however, which allowed two people to marry each other by CONTRACT.This was recognized as a legal marriage.Such marriages were recorded with other contracts, though, not with the marriage records.
Because of the location of Cottage Grove, you might just try searching the contracts in the Siskiyou County Courthouse in Yreka in case that is where they went to get married.Apparently there is another collection of material on Klamath County called the Susie Baker Fountain Papers in the Humboldt County Library; check the above website for details.Good luck - you need it.