In many areas including mine and yours, you can plant oats in spring or fall. Oats are good forage for deer or any animal really. Hay fields can vary, if the one located near you is dark green and not much, if any grass in it, could be alfalfa. If you had a picture of it, could tell you for certain. Just a thought. If the fields are mostly grass, it could be a multitude of things. Sounds like you are in a place where food plots will work good.