Lillie Mae Harris, a 14-year employe for the U.S. Postal Service has allowed neither sleet, nor rain nor dark of night to slow down her fund-raising efforts for those less fortunate than herself.

The 57-year-old Harris recently completed a 25-mile walkathon sponsored the March of Dimes Birth Defects Foundation, and raised more than $1,000.

She has also raised money for the American Cancer Society and frequently invites needy persons into her home and furnishes them with clothing, shelter and emergency pocket money.

The Postal Service recently recognized Harris' achievements and presented her with the agency's Community Service award. Harris, a custodial worker, was one of six postal employes chosen from five regional offices for the award established this year to honor employes who have distinguished themselves through community volunteer work. 1st Woman to Head Local Mensa Group

Amy E. Shaughnessy of Southwest has been elected chairwoman of American Mensa Ltd., the organization for persons who score in the top two percent on IQ tests. She has been a member of the local Mensa society since 1973 and is the first woman to hold the office in the society's 25-year history.

Shaughnessy served as membership officer for the organization in 1978 and as the local secretary in 1979 and 1980 and later went on to serve as Middle Atlantic Regional Vice Chairwoman in 1981 and later elected to the post of First Vice Chairwoman in 1981. She cochaired the annual national meeting held in the District last year.

An editor and manager for various publications, she is currently director of publications for the American Educational Research Association, a professional membership society of educators and researchers. Two Teachers to Get Presidential Awards

Clemontene M. Rountree, a science teacher at Alice Deal Junior High School in Northwest and Rosalie Ann Dance, a math teacher at Ballou Senior High School in Southeast have been selected to receive Presidential Awards for Excellence in Science and Mathematics Teaching by the National Science Foundation.

Rountree and Dance were two of the 104 science and math teachers at junior high and secondary schools across the country who received the award along with a $5,000 grant from the NSF to be used over a two-year period to supplement science and math programs at their schools.

The teachers were selected by a panel of fellow educators and researchers and judged on classroom performance, student progress and professional endeavors.