Eunostus

In Greek mythology, Eunostus or Eunostos was a goddess whose image was set up in mills, and who was believed to keep watch over the just weight of flour.

Promylaia ("the one that stands before/protects the mill") was another name for a goddess of the mills, who was worshipped in the same fashion as Eunostus. Both Eunostus and Promylaia could actually have been mere epithets of Demeter.