I love this one too, how it goes through the seasons

Working in the frosty weather when the stones are stuck togehter
Lifting divots, soil and heather as I prise them off the ground
And little work is done until the weak and wintery sun
Loosens up the icy grip and I can lay me hammer down..

and then, come spring...

Stones taken from the land are warm under the hand

Bok as in one of the trio who sings "John Barleycorn"?