Very interesting find! I take it that it is made of wood, and if it is I would presume that it would be a wooden maul/mallet. I wouldn't be used in processing buttermilk. To make buttermilk you need churning paddles.
As a mallet, it may have been used in mashing berries for pemican.![]()
Where do you live? A few of these were found in Oregon and in Nevada caves. This is why I ask.