AS a little girl, Mamie Garvin Fields loved to visit her grandfather's farm 10 miles outside Bamberg, S.C. One of her favorite spots was a nearby marsh area called Lemon Swamp, a labyrinth of pine trees, oaks, and ferns that offered a cool haven in the steamy heat of summer.
''(The swamp) smelled like fresh herbs,'' she recalls, basking in the memory of her childhood hideaway.
For Mrs. Fields, an educator and a spirited community activist, vivid images from her past unfold as effortlessly as azaleas blooming in the Charleston sun. Her voice resonates with warmth as she describes her first experience teaching in a rural school on John's Island near Charleston, working as a seamstress in Boston to earn money for her trousseau, establishing the first day-care center in Charleston, and fighting for better housing for blacks.
Mrs. Fields, well known in South Carolina for her public achievements, which earned her the state's Senior Citizen of the Year award in 1971, reveals the richness and joy of her personal life in a remarkable oral history recently published as a book: ''Lemon Swamp and Other Places: A Carolina Memoir'' (The Free Press, New York, $16.75).
Mrs. Fields lives in a modest white frame house on the site where she was born 96 years ago. Settling into a flowered armchair in her comfortable living room, she describes how the book came about.
''I started by writing letters to my three granddaughters, writing down the various occurrences from everyday life I wanted to tell them,'' she says. One Christmas about a decade ago she presented the letters to her grandchildren, explaining, ''I want you to know what happened way back yonder.''
One of her granddaughters, Karen Fields, who teaches sociology at Brandeis University near Boston, took a special interest in the letters. Together, working from the letters and their conversations taped over a period of years, they set down the account of life in the segregationist South.