Margaret Mortimer was born 2 May 1304 to Roger Mortimer, 1st Earl of March (1287-1330) and Joan de Geneville (1286-1356) and died 5 May 1337 of unspecified causes. She married Thomas de Berkeley (c1310-1361) May 1319 JL .
Children
| Name | Birth | Death | Joined with |
| Maurice de Berkeley, 4th Lord Berkeley (c1330-1368) | 1330 | 3 June 1368 Berkeley Castle, Berkeley, Gloucestershire, England, United Kingdom | Elizabeth le Despenser (c1325-1389) |
| John de Berkeley (c1330-) | |||
| Roger de Berkeley (c1334-) | |||
| Alphonsus de Berkeley (c1337-1350) | 1337 Berkeley, Gloucestershire, England, United Kingdom | 1350 | |
| Joan de Berkeley (-1369) | |||
Footnotes (including sources)
| ‡ General |
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