I am a beginner at the genealogy thing, and I can use some advice.

On my mother's side of the family I've had some trouble tracing back and if anyone has any advice that might be able to point me in the right direction it would be helpful.

Mother maternal grandmother's maiden name was Calvin (Anna Katherine), born in Jackson County, Oregon around 1923. Her father (as evidenced by Census records from 1920 and 1930) was named John Calvin. He was born around 1871 in Oklahoma. His mother was also born in Oklahoma, his father in Pennsylvania.

The 1930 Census shows Anna Katherine as being "Cherokee--mixed blood" and her mother was white, so I suspect that John's father was possibly married to a Cherokee woman in Oklahoma.

With John Calvin being a relatively common name, does anyone have any suggestions on how I might trace back because I know NOTHING about his family of origin other than the birth places of his mother and father. And with Oklahoma not being a state when he was born it's not well recorded in the Census.

Thanks!