Elizabeth Cook's Maiden Name

It would appear to be Cuvdall on the death certificate, though upon closer examination it could be Cundall or Crandall. She married Joshua Cook prior to 1857. 1857 their son Richard Newton Cook was born. On his (Richard's) death certificate it says he was born in St Charles County, Missouri. I haven't found information on Joshua and Elizabeth Cook. Possibly did migrate thru Kentucky to Lincoln County Missouri where we do find Richard Newton Cook. Would be great to clear up the this line of the family.