While we are so off-topic, I have read several folk lyrics (in a Gammon book I think) involving grinding, though this is usually been done by Millers and involves rhyming 'sack' with 'back', if I remember aright. My friend points out that some blues songs feature similar metaphors, either with a plain and simple 'organ grinder', or with a 'mill', which in one famous case sung of by a woman 'done broke down', or coffee-related grinding. I don't know of any direct British or Irish to blues lyrics links on this line, though I know some blues ballads are versions of ballads whose life began this side of the Atlantic.

Sadly, none of the Millers appear to have made it into Child.