While I don't believe that the complex formations commonly seen on the internet are anything but man made, the intellectual merits of your statement demand some rebuttal. If an advanced civilzation visiting another planet found that the governing institutions and the mainstream media were not willing to admit the existence of the visitors much less convey any communications from them to the general population then I would not think it terribly unlikely that the visitors would seek other means of communication - especially symbolic as the message would be covert enough not to arouse the ire of the governing powers or create general panic yet decipherable enough that intelligent people would "get the message" after a little cogitation. Plus, symbols can also convey information subconsciously which a visitor of advanced means might find to be ultimately more meaningful.
It's not too unlike the approach we might take with say a tribe of people still unaware of modern civilzation. If we were going to be gentle and humane about our introduction we would first make "offerings" as with the old cliche of leaving pots and pans in places to be discovered and picked up by the "natives." We would go about it gradually and with circumspection and in a way "symbolically." Not knowing the language we would at first be required to use hand gestures.
The idea of an advanced civilization using cryptics for commmuncation doesn't seem outlandish to me.

<<Here are some of the circle makers. They are well known, well publicized groups.>>
Re: www.circlemakers.org/new_documents.html

First and foremost, those are mainly the circles made by the old school guys with boards and ropes.

Second, because of that, the "estimated crop damage" is also limited.

Third, "yet the circle makers continue on without prosecution as far as I can tell. What is up with this?"is a question I have already answered above.

My question to you and others is: Why don't you go to England yourself to check all this out, find some some Brit friends here who can unravel these things, and/or do more real investigating as I have so you, too, can find the answers?

Let me know after you do all three as I have!

"The idea of an advanced civilization using cryptics for commmuncation doesn't seem outlandish to me."

I would see that as unlikely. Since we are both just speculating I say there is an equal chance that they would make their presence known in a very clear manner. Perhaps a radio broadcast or they might make a show of it with some big production right out of Hollywood. I think an arrivial of a ship is less likely simply because there is nothing outstanding about our little planet to attract them here. I think the first proof we might ever have would be from a radio signal either from their home world or some machine of theirs traveling through space.

If they have the ability to travel here they would not allow somethign as trivial as government denial stop them from making themselves known to us. There is zero evidence of any visits so far and mere stories by so called abductees are not convincing. When and if they ever visit I think we will know without any doubt.