Mary Emily Eaton was born in Gloucestershire, England. She attended private schools in London before receiving her formal education in art at the Taunton School of Art in Somerset. She also studied at the Royal College of Art and the Chelsea Polytechnic in London. She was originally employed as a painter for Worcester porcelain. In 1909, Miss Eaton went for a long visit with her siblings in Jamaica, where she began to paint butterflies. She then went to New York City and spent 20 years as an artist for the New York Botanical Gardens. There she was the principal illustrator for the NYBG's illustrated serial Addisonia, and did the illustrations for the famous four-volume book The Cactaceae (1919–1923) produced by Britten and Rose. Her work also appeared in Contributions from the U.S. National Herbarium and National Geographic Magazine, and was exhibited at the National Geographic Society in Washington, D.C. Her work in Jamaica led to a series of wildflower paintings later compiled in The Book of Wildflowers (1924). She was awarded the prestigious Grenfell Medal of the Royal Horticultural Society in 1922. Her impressive artistic legacy can still be found at the NYBG, NGS, and in the permanent collection of the Smithsonian Institution.