Response from W&E Treasures, hopefully they get a response with a positive ID!
Hi, Dennis—
I'm not sure, but my best guess is that your Valley Forge souvenir item may have been attached to a key ring, per the loop at the top. As for what it could have contained, well, I suppose almost anything... however, one possibility that comes to mind is penny matches. Judging from the photo with cents added for scale, the length of the item (minus the loop) would appear to be about 1-3/4", which also happens to be the length of a penny match. If that's what it held, there may be one or more surfaces which are textured to permit striking.
I found several listings for a tiny medallion/charm of the same "cannon" design, made by Bates & Klinke of Taunton, MA, a firm specializing in little metal souvenirs. However, no dates of manufacture or other details were provided. Shown below, it generally retails in the $10–20 range.
There was a 1957 Boy Scout jamboree held at Valley Forge, but I don't your find is related to it. Most of those souvenirs have an emblem depicting Washington kneeling in prayer, rather than the cannon shown on yours; and, of course, they also bear some sort of Scout insignia or related mark.
W&ET forwarded photos of your find to the Encampment Store (gift shop) at Valley Forge National Historical Park, to see if it's included in their existing or past inventories. When/if we hear anything from them, I'll write to you again with the details.
All the best,
Mark