Tolkien hasn't been dead long enough....to my understanding, for such things to be legally released into the public domain, under most laws the author needs to have been dead for fifty years...Tolkien died in, what, 1970? that still leaves a decade or so before such a thing can happen. And that's just for Lord of the Rings, I have no idea how it would play out with things like the Silmarillion, having technically been written by JRR himself, but edited and published by Christopher Tolkien.
so, yesh, a dive into the Dark Side of the Internet is all that can help you now....