Rando, trouble is this thing looks had forged. There seems to be a shadow of the forging running from the 'eye" down the piece a ways. None of even the earliest sickle bar mowers had hand forged teeth. There is the remainder of a pin that went through the 'eye' though, and there is not a wider face, which pretty much elimiminate any kind of hammer, (as a wedge would have been used to secure it to a handle.) I'd bet twenty dollars to a doughnut on a hunch (say, how much are doughnuts these days?) that what ever it is, that pin was an after thought when the forged weld broke and the thing got shaky.
It looks like the kind of blunt pin that could have been mounted into something. A wild guess might be one of the two uprights off a certain style of early boot scraper.