Margaret de Bohun, Countess of Devon
Margaret de Bohun, Countess of Devon (3 April 1311 – 16 December 1391) was the daughter of Humphrey de Bohun, 4th Earl of Hereford, Lord High Constable of England and Elizabeth of Rhuddlan. She was the wife of Hugh Courtenay, 10th Earl of Devon (1303–1377).
Source: Wikipedia — Margaret de Bohun, Countess of Devon (CC BY-SA 4.0)