Her father was a gardener probably at Mynachdy. The cottage in which she was born is still there. Sturdily built of stone it has two rooms with a fireplace in each of them. The house is built against the side of a stone outcrop so the only windows are in the front. Before the cottage is a garden that still has wild garlic and strawberries growing in it.
By 1851 Mari's father was dead and her mother was described as an independent widow. This would imply that they were not short of money at this time and this is born out by the fact that they had a servant in 1861 - albeit one of only nine years of age. Her mother died in 1866 of old age and was buried in the churchyard on the 2nd of August By 1871, when Mari was 54 (she says 50 on the Census return), her mother was dead and the servant was gone.
With her parents dead she continued to live at Berllan Pitter and, as the years passed, became more and more eccentric gaining a reputation for witchcraft. She was very short with one shoulder higher than the other. Her head, always covered with a shawl, was usually cast down but when she did raise it her eyes were dark and piercing.
It was said that she would visit farms, not asking for anything but with an empty basket over her arm. If she was not given food of some sort she would turn on her heel and leave without saying a word. Then, some disaster would befall the farm. The milk in the churn would curdle or a horse would have a fit. Mari would be sent for, given food and all would be well.
Another story says that late one Saturday afternoon she took a bag of barley to Aberarth Water Mill to be milled and the miller refused. She cursed the wheel and it started to turn backwards and continued to do so until the miller agreed mill the corn for her.
Yet another story tells of a young girl being forced to walk home backwards because she had been caught by Mari stealing apples from her garden.
She died of Senile Decay at the house of her cousin Mary Anne Davies in Clifton Terrace, Aberarth on the 4th November 1898.