This looks quite simple. All these patterns are made of circles. You have to use a string, fix it at some point and run in circles while cutting the plants. Then you have perfect circular patterns.

It must be fun to be part of such a project to fool the world wink

And it is interesting. This image with the circular object really looks like 3.141592654 if you count from the center and if you subdivide each circle into 10 parts.
So why should an alien race use a decimal numbering system like we do? Do they have 10 fingers like we do?
I think it is made by humans.

So how could we make this pattern ourselves? We had to draw some more strings from the middle just like when we cut a cake into parts. And these helper lines will be there to count how many segments you have to pass until you change direction.
It is the same way like you would make it with a spring bow (Zirkel).

Give me some men and I make you such a pattern into the fields or into the snow. As you like.

Models, Textures and Games from Dexsoft