Does anyone know who makes crop circles that appear to be alien symbols?

I’ve always thought they were really odd, and I’ve never really had anyone fully explain what has been done to try and find the root of how these things are created.

I have also heard that some of the symbols put in fields are done by groups of people, but some circles have never had anyone to claim them. I’ve heard things like aliens and what not are just leaving signs, and there are all sorts of theories about them.

I guess I’m just asking for some input on what you think they might be, or where they come from.