https://archive.org/stream/jstor-20563510/20563510#page/n4/mode/1up
a mid 19th century article about bog butter. The author had tasted every example he'd got his hands on. Ewgh.
and also mentioned in 1753
https://archive.org/details/philtrans04498668
though the author isn't sure if it's interesting enough to mention, that bogs preserve things strangely. but it is really.