My impression is that her maiden name is Chapman, daughter of William. It looks as if she had children with a man surnamed Beck, and then was widowed and went back to her maiden name. However, people did lie about being widowed, rather than divorced, or she may have not been married to Beck. However, not finding a marriage to Beck is not proof that it didn't happen- the marriage may have not been recorded, or they married in another church or town and the civil records didn't start until 1837. I would suggest looking for the marriages of the Beck children, which should will list their father's name..