Alma Woodsey Thomas (September 22, 1891-February 24, 1978) was an African-American artist and educator who is best known for her colorful, abstract compositions.
Biography on Wikipedia: https://en.wikipedia.org/wiki/Alma_Thomas

Breeze Rustling Through Fall Flowers by Alma Thomas
1968 / Acrylic on canvas / 57-7/8″x50″ / The Phillips Collection, Washington, DC

Alma Thomas on Artnet: http://www.artnet.com/artists/alma-woodsey-thomas/

Further reading:
https://www.moma.org/artists/47098
https://www.artnews.com/feature/alma-thomas-who-is-she-why-is-she-important-1234599867/
https://news.artnet.com/art-world/alma-thomas-retrospective-1973476

“Alma W. Thomas:: Everything Is Beautiful” exhibition: https://chrysler.org/exhibition/alma-thomas/