In the 19th century in particular decorating butter was popular and there were several different types of antique treen butter markers or stamps available.
There was a straight forward stamp with a carved base ( see images 5 & 6) the most popular being thistles, & roses. The ejector butter stamps made in two parts, where the handle is pushed down onto the butter ( see image 7 & 8) a butter roller, ( see images 3 & 4), these were also used for pastry decorating. and a two piece butter mould which gives a 3d picture like the swan - image 1 & 2.
These antique treen butter stamps were nearly always made from sycamore wood which was thought to have anti bacterial properties and also didn't taint the food.
Sycamore butter stamps come in different sizes and shapes mainly circular but you can get rectangles, and the carvings vary from flowers and animals such as cows and reindeer (rare) to swans, geometric designs and sometimes names and dates. Occasionally you can get 2 for 1 as there are stamps on the handle and the base but these are difficult to find.