I was in a class recently that included looking at some labelled tree cookies – for trees that are relatively common in our area. Each one is about a foot across. I photographed them to study on my large computer monitor.
Some of them have split as they dried and the saw marks are still visible…but the rings show through reasonably well. They would probably show up better if the cookies were sanded a little. There is something unique about each one: the sugar maple looks light colored throughout; the dogwood has wider dark marks (reddish in color) and they don’t appear to be concentric further away from the center); the cherry has a dark center; the white pine shows come places where branches come off and this cookie has the most clearly visible rings all the way out. It is possible to count the rings out from the center to determine the age of the tree when it was cut done.