Thanks for all the input. Hopefully we'll figure it out.
I thought "farm tool" and "blade" too, but maybe I was misleading with my post title. It might not be a tool at all.
My 16 year old son said, "Dad I think it looks more like an old plow seat."
I don't think he's right, but it has some resemblance to the seat on the left in this EXAMPLE picture:
To me it seems like that ridge on the back side around the edge "reinforces" the flat part, meaning there would have been pressure on the front side (my first picture is the front side).
But the thing that confuses me on the front side is that middle channel and the "pin" in the indentation (what I mean is: if you look at the first picture and follow down from the penny, the first thing you come to is an indentation with a pin across it - like the pin was a pivot point or holding something in). And the middle channel seems to have held wood, I think? I swear there are remnants of the wood grain in there.
By the way, the reason I care is that I'm recovering this and other items from an old farm that has a lot of history in town, and the farm has been sold off, part to a private developer and part to the town itself, to be made into a park. I'm detecting the town's part with permission. They're going to start working on the park this spring, so any history will be lost once they start digging (but other history may be brought to the surface - and to my detector!). In the park they left a little greenhouse, and supposedly that will be turned into a little historical display, so I'm trying to find cool things to add to that display.
- Brian
PS - very close to this mystery item I found an iron ring that I posted about (
http://www.treasurenet.com/forums/what/624433-iron-ring-1750-s-farm.html) and someone identified it as possibly a "wagon tongue support ring", i.e. part of a horse-drawn wagon.
Could this new mystery item be part of a horse drawn wagon?