Some farm item? And nice ornate door lock

Saturday I went to hit the field, where I got the Barber and rosie, with Roger. The only coin that came up between us was a 1937 wheat. Apparently neither of us got the right area. It was a little bit of a let down. I even found a few targets that were really good sounding; turns out they were copper/brass slag and a crushed brass elbow. I did pull up a strange item, looks like it is aluminum. It was a bouncy signal. The oddest thing was that when I came to him to show the item, he was digging the exact same thing. He found one, too. Any ideas on this piece? Hoping someone here knows their farm equipment. I don't think it looks like a pedal from a dirt bike, as there is no way to attach any cables. Plus two of them were found..so that would mean someone dumped their bike twice.
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I did also get back to the site with the belt plate and knee buckle. This time I limited myself to 2 hours max. I tried the area across the street where there looked like a concrete thing covered. Like a septic. But the house was gone before the 30's... In the area there was some stone work. Only came up with bullet tips. A lot of them. And the copper ones sounding like coins. ugh. Up near the back shed I did pull up a door plate where there is a defined skeleton key hole. So those who find the keys can see what the plate on a door would look like. It is quite ornate and I cannot tell what it is made from. The black color that had a reddish underneath to me looks like brass. But after a little cleaning it doesn't look like brass at all. If it was iron, it was plated with something which prevented it from rusting. Just a nice item so those can view even if 'junk'.
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That's a beautiful lock plate. Stuff nowadays is so boring in appearance compared to back then. As for the other item, then only thing I can think of is a gate latch.