I am just getting started thinking about tracing my father's family and came across your website.
His name was Wilson Overall, born in Fayetteville, MO in 1906. His mother was mary 'Mammie' Smith Overall from (I believe Throckmorton Co., TX). My father's grandfather was Nathan Overall, mayor of St. Charles in 1860(ish). My father's family left Fayetteville, MO for California somewhere around 1930.   Wilson Overall's brothers and sister were named: Asa, Nathaniel, Solon, Ezra, Ann and Corrin (who dies in a buggy accident around 1910).
Don't know if this helps you at all. In the event that there is any connection I wish you well in your search. There are not a ton of us "Overalls".
Sincerely,
Mary Overall
806 Eucalyptus Ave.
Santa Barbara, CA 93101