[RacerX1166]

You can make it yourself quite easily. Heavy cream whipped until it separates will form butter chunks. Wash off the watery stuff and add salt to taste.
My at the time gf and I went to a Civil War days event and they were making butter on the premises. Even got to try our hand at churning. The lady demonstrating shared the above process. Still do it on occasion but mostly for the wow factor.