Raised on a farm in Mynachlog-ddu, Pembrokeshire, Mari was educated in Ysgol y Preseli before going on to study Welsh at Cardiff University.
Cafodd ei magu ar fferm ym Mynachlog-ddu, Sir Benfro, a'i haddysgu yn Ysgol y Preseli cyn iddi astudio'r Gymraeg ym Mhrifysgol Caerdydd.