Some folks were posting pictures on the internet of arrowhead finds.  You must limit your hunting to private ground, but farms and plowed fields are for some reason fertile places to find all sorts of good relics.   Below are some arrowheads found in Colorado, and made out of petrified wood.

An in situ find, dug up first by a helpful old gopher.

A guy in Oregon taught himself how to make arrowheads out of obsidian, a process known as knapping, and produced these beauties.

The collection below includes a couple of old rifle shells.  White people were told to pinch off the mouth to prevent the indians from reusing them.  The square piece on the right is an old flint from a flintlock rifle that an indian reformed into a scraper.  Thats three different people owning it over the years.  First the guy with the old flintlock rifle, then the indian, and finally the fellow who collected it off the ground.