In 1891, 41% of all Buttreys in England lived in Shropshire. There were 8% of the Butterys there at that time.
A buttrey or buttery was a room or storeroom where barrels and butts of alcohol were stored in medieval times. The name has nothing to do with butter.
I do not know if the Buttreys of Moreton Say in the 1600s were originally cellarers or merely peasants. I have recently discovered a family tree tracing the ancestors of the family to Uffington near Shrewsbury. Nearby is Haughmond Abbey. There is likely to have been a buttery there.