I wouldn't be surprised if those wagon wheels are much older than anyone thinks, maybe as far back as the 1850's. The hubs are more than likely cast iron. The manufacturer, city, and sometimes year can be found cast into the hub. These can be found on the inside flange. If it is there, it is should be visible. Woodjin, that is an incredible find!
Thanks,
In order to open the flange, I will have to take precautions not to destroy it further. It is certainly tempting to look isn't it. I will have to bring some tools with me to carefully remove it. Rest assured I will be very careful.