Civil War item in Iowa Maybe?

Well, Bart at Big Boys Hobbies gave me a heck of a deal on a used Whites MXT last week. It came in yesterday in the mail. I swung it 15 minutes in the yard yesterday to make sure it worked and found some old bottle caps. Took the MXT in the yard today and I am amazed, me and this detector are going to get along great. These finds were found in the same yard I found a Civil War token and Civil War staff officers button in last year as an FYI which is why I suspect CW. I found the 47 wheaty in a hole with a bottle cap and a rusty nail, and what ever the item that sais "US" was about 8" down in a hole with 3 square nails. So folks, what is it? One picture shows the front and the other shows the back of the item, both photos have the wheat penny for size comparison. Thanks