Wikipedia
Edla, traditionally called Edla, Duchess of Venden (Edla, hertiginna av Venden) (10th-11th centuries), was a Slavic Viking age woman. She was the mother of King Emund of Sweden and Queen Astrid of Norway.
Tradition says Edla was the daughter of a West Slavic Tribal chief from Northern Germany. She was brought to Sweden as a prisoner of war c. 1000 at the same time or a little before, the arrival of Estrid of the Obotrites (Estrid av obotriterna). King Olof Skötkonung married Estrid but also fell in love with Edla and took her as his mistress. She became the mother of Emund, Astrid, and probably Holmfrid. Snorre Sturlasson says that her children were sent to foster parents away from the royal court because Queen Estrid was not kind to them. This could indicate that Edla died when her children were small.