Well, here in our local parks, all the trees are tagged with tags like that...
could be, but maybe not. That is the first thing that came to my mind.
There are enough numbers to be a phone number... try calling it... LOL
Yep, here in TN I see these on certain plants that the state tag and watch. Not to far from my house we have a large glade with ground plumb that my buddy found a few years back and the state bought that land and tagged all of the plants with tags like this.
Ya know it has the same number of numerals as a WW 1 dog tag. The one I found had a name on the back. I remember reading they had no set type or material it was made from until years later. (The one I found was aluminium) here's a pic. Maybe it's not a tree?
The numbers on the tag were stamped by hand(they're not straight). The hole looks worn from hanging on a key ring? It's a "one of". Maybe a phone no. in case the keys were lost?? Tony