I advise looking at Clarks in Morgan, Monongalia, West Virginia.
1900 Census Morgan, Monongalia, West Virginia
Dannial W Clark, age 21, born Aug 1878 West Virginia as grandson in the household of John E Clark, age 70
1910 Census Morgan, Monongalia, West Virginia
Daniel Clark, age 33, born West Virginia as son of EW Clark
1940 Census Morgan, Monongalia, West Virginia
Dan W Clark, age 62, West Virginia as head, Widowed with 5 children, ages 10 to 24 years
West Virginia Death Index 1853-1973
Daniel Webster Clark
Died: Sep 14 1959
Monongalia, West Virginia
Father: Eugene West Clark
Mother: Mary Edith West
I assume that Dan and Agnes were divorced with both remarried between 1911 and 1920 as your tree shows Agnes remarried to Homer Evans.
Take a look at the birth entry here:http://www.wvculture.org/vrr/va_view2.aspx?FilmNumber=840895...
The name of the person giving the information is Agnes Belle Evans, mother. The mother's name in full looks like Agnes Belle McGraw.