Some butter churns also have serial numbers that prove authenticity that you can look up online via the US Patent and Trademark Office. Online marketplaces are very popular nowadays and many buy and sell antiques on platforms such as eBay or listings on social media marketplaces. A butter churn is a tool that converts the cream in whole milk into butter. (20% off), Sale Price 50.39 Churns in good condition will sell for a lower price than ones in excellent condition but can still be valuable. It was called a plunger churn because the dairymaid plunged the tool up and down vigorously. >> serving, dishes,