I think it is a "stretch" to call some of those arrowheads. They look pretty crude to be arrowheads. I have a collection of arrowheads that I have found, and they were much better formed, even those that were not finished. I would take a couple of them to some one who collects them or sells them in your area and ask about them. But as to age, if I am not mistaken, most of the indian artifacts in your area wouldn't be prehistoric as these points might show. Good luck and if they are legit, please post closer up photos of them and what the "experts" say about them.