*Agnes de Grey
born about 1370 (or 1380?) Heton, Northumberland, England
died 25 October 1429 Harbottle Castle, Yorkshire, England

father:
*Sir Thomas Grey IV Lord of Hetton
born about 1359 Heton, Northumberland, England
died 26 November 1400

mother:
*Jane (Joan) de Mowbray
born about 1363 England
died (after?) 30 November 1402 England

siblings:
*Maud de Grey born about 1382 Warwickshire, England died 12 or 22 August 1451
Sir Thomas de Grey V of Heton born 30 November 1384 Castle Alnwick, Northumberland, England
died 3 August 1415 North Gate, Southampton, Hampshire, England
John de Grey Earl of Tancarville born about 1386 Wark-Upon-Tweed, Northumberland, England
died 22 March 1420/21 Battle of Bauge, Anjou, France
Maud de Grey born about 1394 died 22 August 1451

spouse:
*Sir Thomas de Umfreville
born 1367 Harbottle Castle, Yorkshire, England
died 14 February 1390 Harbottle Castle, Yorkshire, England

children:
*Elizabeth de Umfreville
born about 1388

biographical and/or anecdotal:

notes or source:
LDS
ancestry.com
From the dates given it seems a better fit that *Agnes was the daughter of Thomas III instead of Thomas IV.