Small suspension balance beam scales of the 19th Century typically had two circular brass dishes or pans, attached through three small holes generally by string, hanging from a horizontal balance beam that was suspended in the center.
Your pieces there do not resemble any part of a scale to my knowledge. Also, the shiny portions showing on your two pieces, judging by what can be seen in the photo, appear to be similar to either aluminum, or chrome plating. My impression is 20th Century manufacture on these.
The rusty square nail is likely the earliest item you have there.
CC Hunter