Hi Squibby,
I think Plumbata is on the right track I would definitely put that onto other forums as mentioned and native american blogs or sites. Someone may recognize that pattern or symbol. That second photo looks like more bone fragments and pieces.
Various grave goods were deposited alongside the bodies inside the passage. Excavations that took place in the late 1960s and early 1970s revealed seven 'marbles', four pendants, two beads, a used flint flake, a bone chisel and fragments of bone pins and points.
This is a passage from this website : http://en.wikipedia.org/wiki/Newgrange
Maybe the term "grave goods" could help in some way?
I know Wikipedia isn't the most reliable source... but maybe that will help?
It was a very common practice (probably pretty much routine) on this side of the Atlantic for people to place items in foundations, walls, chimneys, under doorsteps,under hearthstones, in roofs of their homes (in fact pretty much anywhere in the fabric of a house) as good luck charms, to ward off evil spirits, etc, etc, well into the 18th century, and even in the 19th century in some areas.
If your house dates to the 1700s then I'd expect that pendant and bone werethat kind of thing.
We are in Massachusetts. No lie, when I pulled it out of the wall and realized what it was I had a flashback of Poltergeist and pictures ghosts swirling around my house..."go to the light, Caroline.." Lol