Margaret Mortimer Baroness Berkeley (1304–1337) Parents Roger Mortimer, 1st Earl of March Joan de Geneville, 2nd Baroness Geneville Children Maurice de Berkeley, 4th Baron Berkeley Joan de Berkeley Siblings Edmund Mortimer Katherine Mortimer, Countess of Warwick Agnes Mortimer, Countess of Pembroke Maud Mortimer Joan Mortimer Beatrice Mortimer Geoffrey Mortimer John Mortimer Elinor ferch Roger Mortimer Blanche Mortimer Roger Mortimer Isabella Mortimer Partners Thomas de Berkeley, 3rd Baron Berkeley