Therese Ann Rutherford (born November 2 , 1920 ) is a Canadian -American actress in film , radio , and television . She has had a long career starring and co-starring in films, playing Polly Benedict on the big screen of the 1930s and 1940s, and on The Bob Newhart Show as Newhart's character's mother-in-law. Her first film role was in Waterfront Lady in 1935. She appeared in eighteen films between 1935 and 1937. It was in 1937 that her first notable role came as Andy Hardy 's girlfriend, Polly Benedict, in You're Only Young Once . In the long-running, Academy Award-winning Andy Hardy film series, she played Polly twelve times, with the last appearance being in Andy Hardy's Double Life in 1942. She is one of the few (perhaps the last) surviving members of the "Gone with the Wind" cast.