Margaret Neilson Armstrong (1867–1944) was a 19th and early 20th-century American book cover designer, illustrator, and author. She is best known for her book covers influenced by Art Nouveau. She also wrote and illustrated the first comprehensive guide to wildflowers of the American west, Field Book of Western Wild Flowers (1915). In later life, she wrote two popular biographies and three mystery novels. No. 1 on The New York Times Nonfiction best seller list for 1 week, from the issue of July 25, 1938. Wiki link