Dear Mr. Duncan,
Thank you for posting your request on History Hub!
This pin is the shield of the 24th Armored Engineer Battalion. This unit served in the 4th Armored Division during WW2 in Patton’s Army.
The National Archives does not appraise or look at privately owned documents or artifacts.
The ABAA (Antiquarian Booksellers Association of America) is a trade association for dealers of rare books and manuscripts. You may be able to find a listing for a qualified appraiser in their member directory. The National Archives is providing this information as a courtesy. We do not endorse or recommend private appraisers.
Please see their website at http://www.abaa.org/
We hope this is helpful. Best of luck with your research!