Mary Jane Conyers Smith, 67, a retired restaurant cook who was honored for her volunteer work with welfare rights and senior citizens organizations, died of a heart attack Wednesday at her Washington home.

Mrs. Smith was a cook at Washington restaurants, including Merriman's and the Harrison Cafe, for 20 years before retiring in the late 1950s for medical reasons.

She then was an unpaid teacher's assistant for pre-schoolers at Watkins Elementary School from 1965 until about 1969.

Mrs. Smith began her welfare rights volunteer work in about 1970 when she was elected chairman of the Willing Worker Welfare Rights organization, where she served both as an adviser to people seeking welfare assistance and to people trying to find work in order to escape from welfare.

In May, 1973, she was elected chairman of the D.C. Citywide Welfare Rights Organization, a position she held Until 1977, when she left because of a heart ailment. She continued to help the organization from her home and remained chairman until her death.

She also was on the board at Friendship House and worked with the Metropolitan Citizens Advisory Council's Senior Citizens Task Force for eight years.

Among her awards are the D.C. Mayor's Bicentenial Plaque for outstanding volunteer work, a sterling silver plaque from the Metropolitan Citzens Advisory Board and a certificate of merit from the District of Columbia.

Mrs. Smith was born in Nashville, N.C., and lived in Washington for 45 years, where she was a longtime member of the Liberty Baptist Church and its Flower Club. She also was a member of the Grand Lodge A.I.O. of Moses, Chapter 52.

Her Former husband, George H. Smith, died in 1977.

Survivors include four sons, Joseph, John, Thomas and Raymond, all of Washington; a daughter, Adeline Bolden, of Landover; three sisters, Maggie Wright, of Rocky Mount, N.C., Janitha Hughes, of Hopewell, Va., and Gertrude Crenshaw, of Wilmington, Del.; two brothers, James and Richard Conyers, both of Wilmington; three grandchildren whom she reared, Sandra McPherson, Anthony Smith and Alonzo Ayers, and 14 other grandchildren and three great-grandchildren. A daughter, Tempie Ruth Ayers, died in 1957.