Anna Margareta Holmgren-Strömbom was born in Uppsala, daughter of Professor Fritjof Holmgren, an internationally renowned physiologist, and the women’s rights campaigner and author Ann-Margret Holmgren. She qualified as a schoolmistress and followed in her mother’s footsteps.
In her autobiography Hemmet med de öppna dörarna, 1939, she writes more about her parents than about herself, and she appears to have had a very strong bond with them. However, she came into her own as a writer of tales and published several collections of tales, such as Ur den blåmålade kistan, 1913, and Svenska folksagor, 1921, under the pseudonym Sago-Greta.