I'm in Indiana and have found probably a half dozen like that size. I would date mine in the mid to late 1800's based on coins found in the same location. I usually find them near old school houses dated around the late 1800's as well. Nice find! Keep hunting that area bound to be more stuff. Indian heads, barber quarters maybe..
Hard to say - you end up finding a lot of D Buckles at newer and older sites.
The smaller ones usually come in on the same target ID numbers as Quarters.