You know, I have found a number of dog tags over the years, save it, because when you have only one, it's no big deal, BUT, when you have a couple of dozen, they are a really good " show & tell" type of thing people like looking at. I also think there's a sub-forum on T-Net for dog tags,
Just my opinion, but to me, the ones found in my area are different. We have dog tax tags from the very early 1900's, up to around 1970. The tag actually said "Dog Tax". After that, we no longer had to pay a dog tax, so the tags were eliminated. The Rabies and name tags became popular simply because the municipalities made you get Rabies shots for your dogs. I also agree with Spailroad on displaying them in a case. I have over 20 "Dog tax tags" and over 50 Rabies/name tags. When you find that many of them, they do look great in a case for all your friends to see.
Trapper340, added note, in addition to dog tags, I've done the same with marbles, a few?, again not a big deal, but I now have a couple of hundred that look great in a large glass bowl, and KEYS, love finding the keys, cars, house keys and everything in between, all in a large old style mason jar. One item I regret NOT saving is all the old Pocket Watches I have found over the years, sometimes just the outer ring with stem attached, others with the rusted guts still in it etc. All of them cleaned up, would of made a fantastic display in a frame now, just as Trezurehunter had said. Opportunity lost for me now, but for newer guys, something to think about?