Greenfield was born in Parmele, North Carolina and grew up in Washington, D.C. during the Great Depression in a housing project called Langston Terrace, named after John Mercer Langston, that provided a warm childhood experience for her. She was the second oldest of five children of Weston W. Little and his wife Lessie (née Jones). A shy and studious child, she loved music and took piano lessons. She graduated from Cardozo Senior High School in 1946 and attended Miner Teachers College until 1949. In her third year, however, she found that she was too shy to be a teacher and dropped out.
Greenfield began work in the civil service at the U.S. Patent Office. In 1950, she married World War II veteran Robert J. Greenfield, a long-time friend. She began writing poetry and songs in the 1950s while working at the Patent Office, finally succeeding in getting her work published after many years of writing and submitting poetry and stories. After joining the District of Columbia Black Writers Workshop in 1971, she began to write books for children. She has published more than 40 children's books, including picture books, novels, poetry and biographies. She says that she seeks to "choose and order words that children will celebrate".
Dismayed by the depiction of blacks and black communities in popular media, Greenfield has focused her work on realistic but positive portrayals of African-American communities, families and friendships. These relationships are emphasized in
Sister (1974) a young girl copes with the death of a parent with the help of other family members,
Me and Nessie (1975) about best friends,
My Daddy and I (1991) and
Big Friend, Little Friend (1991) about mentoring. Her first book,
Bubbles (1972), "sets the tone for much of Greenfield's later work: Realistic portrayals of loving African American parents working hard to provide for their families, and the children who face life's challenges with a positive outlook." In
She Come Bringing Me that Little Baby Girl (1974), a boy deals with feelings of envy and learns to share his parents’ love when his baby sister arrives. The poignant
Alesia (1981) concerns the bravery of a girl handicapped by a childhood accident.
Night on Neighborhood Street (1991) is a collection of poems depicting everyday life in an urban community. One of her best-known books,
Honey I Love, first published in 1978, is a collection of poems for people of all ages concerning the daily lives and loving relationships of children and families. Her semi-autobiographical book
Childtimes: A Three-Generation Memoir (1979) describes her happy childhood in a neighborhood with strong positive relationships. In the introduction to that book, she explains her interest in biography:
People are a part of their time. They are affected, during the time that they live by the things that happen in their world. Big things and small things. A war, an invention such as radio or television, a birthday party, a kiss. All of these help to shape the present and the future. If we could know more about our ancestors, about the experiences they had when they were children, and after they had grown up, too, we would know much more about what has shaped us and our world.
In 1971, Greenfield began work for the District of Columbia Black Writers' Workshop, as co-director of adult fiction and then, in 1973, as director of children's literature. That group's goal was to encourage the writing and publishing of Africa-American literature. She was writer-in-residence at the District of Columbia Commission on the Arts and Humanities in 1985-86 and taught creative writing in schools under grants from the Commission. She has also lectured and given free workshops on writing of African-American children's literature. She is a member of the National Literary Hall of Fame for Writers of African Descent and a member of the African-American Writers Guild. Since 1991, most of Greenfield's books have been illustrated by Jan Spivey Gilchrist.
In 1983, Greenfield won the Washington, DC Mayor's Art Award in Literature. In 1990 she received a Recognition of Merit Award from the George G. Stone Center for Children's Books in Claremont, California. She won the Award for Excellence in Poetry for Children, given by the National Council of Teachers of English. She also received a lifetime achievement citation from the Ninth Annual Celebration of Black Writing, Philadelphia, PA, 1993; the Virginia Hamilton Literary Award; the Milner Award; the Hope S. Dean Award from the Foundation for Children's Literature; the American Library Association notable book citation; and the National Black Child Development Institute Award, among others.
Greenfield lives in Washington, D.C. She and her husband have a son, Steve, a daughter, Monica, and four grandchildren.