They were married in 1904. Does the marriage record not name his parents?
Name: Frederic Arthur Wynnamer Gender: Male Marriage Date: 26 Dec 1904 Marriage Place: Freedom, Waseca, Minnesota Spouse's Name: Rose Sophia Holz Spouse Gender: Female Event Type: Marriage FHL Film Number: 1320462
I found him in the 1900 census in Byron, Waseca County, Minnesota, and he is a good ten years old than he is in the 1905 and 1910 census. Born June 1867, aged 32, born in England, both parents also born in England, immigrated 1876, farm laborer, living with the family of Walter Brisband.