Eastern Utah is littered with dinosaur bone, although I'm told it is protected from public collection by antiquities law. However, that doesn't seem to stop some vendors from getting and selling it. Likely private property grabs. The high grade stuff shows black bone grain divisions with multi-colored agate deposits.
I've managed to buy a few small slabs, not real high grade, but interesting nonetheless. I also picked up 3 pounds of un-cut gembone from a garage sale... of all places to find dino bone.
For more on Gembone.