Hi, I joined so I could post this in case anyone is interested. I've recently been photographing a previously undocumented section of Oak Hill Cemetery in San Jose and came across Frances Cobb's marker: you can view the memorial that I created in Findagrave here: https://www.findagrave.com/memorial/229377828/frances-cobb
I also found a record of Alvin Lafayette Cobb's marker in an index of headstone inscriptions at Oak Hill Cemetery that was compiled a number of years ago by the local historical society; it was later microfilmed and is now available on Familysearch.org. The index indicates that Alvin's inscription read as follows: Col. A. L. Cobb, M.D., 1818-1904. The marker was transcribed in one of the earlier cemetery surveys which occurred in the 1930s-1950s era. However, the index was not seen during the historical society's survey in 1982. (Missing grave markers are a common issue at Oak Hill Cemetery as they tend to sink into the soil over time and become buried.)
You can read the memorial that I created here: https://www.findagrave.com/memorial/229976544/alvin-lafayette-cobb
I wanted to thank everyone for posting the research that was the basis of the bio that I wrote up.