Joan of Kent
Joan, countess of Kent, princess of Wales (c. 1328 - 1385), daughter of Edmund of Woodstock, first earl of Kent, and Margaret Wake. She married Edward the Black Prince in 1361 and had her second son, the future king Richard II, with the prince, in 1367.
For her life and marriages, see Richard Barber, 'Joan, suo jure countess of Kent, and princess of Wales and of Aquitaine [called the Fair Maid of Kent] (c.1328-1385)', in Oxford Dictionary of National Biography, ed. H. C. G. Matthew and Brian Harrison (Oxford: OUP, 2004), http://www.oxforddnb.com/view/article/14823
to find all occurrences of this name.