It only took 2 1/2 years to identify what it is, but it's now solved. It's called Kissi Money. After talking with the owners of the barn, which is now gone, they think these were probably brought back by their grandfather. They said he spent some time with a British Army unit in Sierra Leone during WW2, and showed me some pictures of him during that time. I gave them back, so they could be passed down to their family members.