flat button.

I went out to my 1830s farm site for a couple hours after a good rain storm. It's been awhile since I have been out digging with the drought here. I tried going out a couple days ago but the ground was so hard I could barely get my shovel in the ground. The 1864 IHC is the best one I've found...

I found this flat button the other day at a mid 1700's site. I was hoping when cleaned it was a GW button but there are no visible markings on it. Can anyone tell me what type it is and how old? Thanks.