Fabulous mystery in one hole! Congrats! White piece with dots is pipe stem. At Jamestown they found some folks buried in pits. The flat bones could be either pelvis or shoulder blade. I recommend you douse the area and mark off any indications of a larger disturbance of the surrounding ground. If this is a human burial
and the individual was lain out, the dousing will reveal the outline of the grave. If you do find that to be true, then the next step would be to have the bones evaluated by a professional. It in some ways look like a child's treasures but why it would include bones, and that many coins is beyond me. What's on the fronts of the buttons?