Where did Martha Washington work?

No, Martha Dandridge Custis Washington [June 2, 1731-May 22, 1802] didn't have a job in the sense of carrying out certain responsibilities for which she received regular pay. But she was expected to carry out joblike responsibilities. Specifically, she was born, and married into, the wealthy landowning class in the subsequent United States of America. So she received a dowry and an inheritance. In return for economic security, she received a private education that prepared her to take her place in society as a hostess and as the manager of the household.