Matilda of Swabia
Matilda of Swabia was a daughter of Herman, duke of Swabia. Her sister, Gisela, was the empress of Conrad II. Matilda was married first to Conrad of Carinthia, duke of Worms, (+1011), with whom she had a son, Conrad the Younger. Her second husband was Frederick of Upper Lorraine (+1026), with whom she had three children, Sophia, Frederick, and Beatrice, who later ruled Tuscany and Lorraine with her daughter, countess Matilda. The elder Matilda and her son Frederick both died in 1033, and her sister empress Gisela adopted Sophia and Beatrice. In Ekkehard IV, Casus sancti Galli, Matilda is mentioned as slipping a ring on the finger of a monk of St. Gall after a mass.
For more on Matilda and her letter to King Mieszko, see Brygida Kurbis, "Die Epistola Mathildis Suevae an Mieszko II, in neuer Sicht Ein Forschungsbericht," Fruhmittelalterliche Studien, 23 (1989), 318-43.