Well her christian name was Mary Ann and in 1871 she said she was born in Builth.
1871 census transcript.
EVANS Moses, h, m, 24, ag lab, HEF Stapleton, Llowes Village, /f62/p5
EVANS Mary Ann, w, m, 19, -, BRE Builth, Llowes Village, /f62/p5
EVANS Bryan, s, -, 1, -, RAD Llowes, Llowes Village, /f62/p5