Nice find KG6YLL! I have a few questions?
Is it stamped brass or solid cast?
Is the center disc domed or slightly raised?
I have never seen a tongue that is flat?
The picture might be deceiving but is the loop slightly arched? I have yet to see a tongue that is arched, all the ones I have dug or seen are straight.
I attached a few pics. of the baby buckles I have dug lately and most of them this last year. They are all 1870's except the one to the right of the penny which was dug out of an 1850's gold rush camp. I believe it to be from a neckerchief or pre tied neck cravat as Kuger mentioned. The rest I don't have a clue unless for dolls as mentioned before.
The buckle above the penny has a patent date of Feb. 20, 1872 and still has some cloth under one side that is folded over. The last picture, I included a full size mans stamped brass T&W buckle for scale.
Hope this helps!
Ironman!