old buckles

Found this buckle frame near an historic farmhouse in Hunterdon county, NJ. The dimensions are 85mm x 50mm. There doesn't appear to be any design. Any insights as to type (shoe buckle?) and age would be greatly appreciated. Thanks.

All of these were found in northern new jersey in 2012 , been trying to put some dates to them and figure out which are the older ones but i know very little about buckles, if anyone has any input i would love to hear it! Also threw in a pic of a lock that I think is from the late 1800s and...