Although it is tempting, with our view back over the centuries, to assume this is faux Doll's Head, and that image may well have been in the action fillers mind as he shaped the action, I think it is little more than a raised 'shield' to lead ones eye onto the raised, file cut rib of a tool for harvesting food.
I am in no way denigrating the piece but I think we have to guard against over romanticising what was in effect a very nicely finished 'tool'.