Re: bone game pieces
Maybe that hour glass design is a Viking symbol.

I'm not really being serious. But the bird track design, the MMMMMM design, and the hour glass design on some of your artifacts look very similar to the Viking "alphabet".
The Vikings came to North America around 1000 years ago, and I know a lot of people believe that the Vikings "intermarried" with the natives. Some people believe that the Mandan's sophisticated architecture and the way some of their villages/towns were constructed, and so on, was a Viking influence. Of course, most professional archaeologists don't believe this and some attribute the technology to be a Mississippian influence.
Many of the early explorers who lived with the Mandans wrote that some of the Mandans looked European. Back then many believed (or wanted to believe) that the Mandans were Welsh Indians, descendants of Prince Madoc. George Catlin wrote that 1/6 of the tribe had light colored hair, blue eyes and oval faces. Personally, I don't believe the Vikings (or Prince Madoc) had any connection with the Mandans, but a lot of people in North Dakota like to talk about it. I always believed that some of the early French traders, and others, mixed with the Mandans and that could account for some of the physical characteristics noted by the early explorers. The smallpox epidemics of 1781-1782 and 1837-1838 killed most of the Mandans, but a few survived and there is nothing in their appearance, language or their oral history to suggest that they are descendants of the Vikings or Price Madoc. In addition, scientists can tell by the shape of the skulls that the Mandans were distinctly Native American and Siouan.
Here are Viking symbols and a link. Oh, by the way, this shouldn't be taken seriously, just for fun!
http://www.sunnyway.com/runes/index.html
