Sorry for not including enough information. Arthur Scofield was born on 29th of April 1914 in Moorhead, Clay, Minnesota. HIs brother was Willard John Scofield, born 17th of January 1912. Their mother was Clara Matilda Gredvig, born on the 28th of April 1885 in Lura, Fairibault, Minnesota. The 1920 Census shows Clara married to a man called William John Scofield and they live in Missoula Montana. The 1920 census shows only Arthur living with Clara and William Scofield, I don't know where Willard was.
In the 1930 Census, Willard and Arthur are living with Clara and William Scofield, in Portland Oregon, and they are named as his stepsons. Though I believe William Scofield adopted them, and that is how their name was changed to Scofield, and that is how I ended up a Scofield. I am eager to find out what my name "should" have been.
How do I find out their biological father's name? This Family Data Collection index provides the only clue that I can find that Clara was ever involved with anyone other than William Scofield.
I can't find Clara in the 1910 Census, becasue she was no longer Clara Gredvig, and not yet Clara Scofield. I have searched for a Clara Dahl but I can't find one that seems to be her.