Since we are nearing the time of Disclosure I thought this could be an attempt by the Galactics to tell us that the time for them to directly broadcast to the people of the Earth simultaneously is at hand (see the diagram for more details).
The Galactic Federation is capable of broadcasting to our manmade electronic devices whether its computers, television, radios, smartphones and etc. And they can even do this even if our devices are switched off, this is because they can also distribute energy/electricity wirelessly anywhere in the world. This kind of electrical capability was demonstrated by Tesla during his time.
Having this crop circle means they are ready to broadcast and download several digital data content whether video, audio and etc. They chose to do this in California possibly because we all know that it is the home of Hollywood where most of the worlds entertainment, movies and films are made.
The following Diagram - Illustration is a possible interpretation of this Crop Circle: