You should have a New York State Geological Survey office in your state government. contact them, or any Geology department at a local university, and they will know where you can look for flint, chert, agates, jaspers, and other silicates. The Surveys were not established for this purpose- rather to locate and identify rock strata within the state to aid mining interests. But, the maps exist, none-the-less, and you can use them, too. Checking with Lapidary Arts stores/schools, and gem stores may also get you directions to find these kinds of rocks.
Good luck on your search. :thumbsup: