CHELMSFORD -- Martha W. (Thompson) King, 67, a Chelmsford resident for more than 10 years, and the former gift shop manager at a museum in Harvard, died yesterday, June 14, at her home. She was the wife of the late Robert King.She was born in Worcester on April 12, 1938, a daughter of the late William I. Thompson Jr. and Edith (Briggs) Thompson. She received an associate's degree from Green Mountain College in Vermont.Before retiring, Mrs. King was the gift shop manager at Fruitlands Museum in Harvard. She also worked as a counselor. She was a former Sundbury resident.She is survived by a son, Stephen R. Wilkinson of Londonderry, N.H.; two brothers and sisters-in-law, William I. Thompson III and Diane Thompson of Falls Church, Va., and Francis J. and Lorrie Thompson of Millbury; two sisters and a brother-in-law, Carolyn B. Thompson of Millbury, and Elizabeth T. and Errol Rick of Chelmsford; her stepmother, Helen Brown Thompson of Millbury. Mrs. King also leaves her best friend, Diana L. Mangsen of Shirley; and several nieces and nephews.