I'm sorry to say I haven't found anyone in the Brunswick, MO area in my tree yet. Then again, maybe Jacob's parents hail from that area and I just haven't found them yet!
Here is what little I can tell you about Clarence and his parents and sister:
Clarence A. Davison (no clue what the middle name is): Born 11/29/1887 in Sullivan, Sullivan County, Indiana. Died 7/14/1961 in Des Moines, Polk County, Iowa. Buried 7/17/1961 in the Highland Park Cemetery in Kirksville, Adair County, Missouri. As of the 1900 census he was living in Danville City, Vermillion County, Illinois. His WWI draft registration card dated 1917-1918 says he was living in Springfield, Sangamon County, Illinois at the time.
He married Martha Mae Haynes (1900-1923) sometime in 1917. They had four children: Lionel Lincoln (1916-1991), Wilma Maxine (1919-2005), Bobby Tipton (1921-?) and Martha Loretta (1923-1927).
Clarence had a sister named Carrie, but I have no dates on her. She married a man surnamed Miller and had a son named Layton, but that is all I have on them.
Clarence's parents were Jacob Lincoln Davison and Harriet S. Evans. He was born in September of 1864 and might possibly have had another wife surnamed Cessna. I have no further info on Jacob.
Harriet was born sometime before 1875 and died sometime before 1972. And that's all I have on her.
No parents or marriage date for Jacob and Harriet.
I appreciate your interest and help. I know it's not much to go on. I only discovered the names of Clarence's parents about 2 or 3 years ago when we finally gleaned enough info on Clarence to get his birth certificate. Now I'm stuck mostly on his parents and sister.