I would say it's probably not a gear, due to the small size of the "teeth". More likely it was a wheel you turned by hand and the edge was cut like that to keep your fingers from slipping. Might have had a shaft pressed into the center. Hard to say what it might have turned.
Maybe a materials guide for rolling stock (paper or fabric).
I've seen plastic ones on older dot-matrix printers to keep the paper aligned to the platen.
Maybe from a typewriter?
Is the hole in the center threaded or smooth?
And how thick is the piece?
It is slightly thicker than a large cent. Very sturdy. I am guessing yall are on to something about being a knob or turner for something. A lantern would make perfect sense I will do some checking on those. Not sure about the tractor valve knob. Plenty of farming in the area so certainly a possibility but not sure how to look that one up. Thanks for the suggestions.
I have to say, I've never seen a lamp wick-adjuster disc that's the same diameter and thickness as a US 50-cent coin. (Note the US penny in the photo, for size-scale.) But I do not believe I've seen everything, so perhaps such a thing does exist.
I do agree that the "knurling" on its edge suggests it is an adjuster-wheel of some type.