I think this is a great idea for a challenge.  I may not get time to get out and take any in the next two weeks so here's some "pre-shot" photos that fit the bill.

Spiral Pattern This is a different perspective.  I had to lean over the railing and shoot handheld in low light. 

Here's another from my trip to Shaker Village in KY Vanishing Pattern 

Finally, a different kind of Floral Pattern This was a bush that grew in a spherical shape with the star shaped flowers on the outside and stems converging on the inside. 

Looking forward to seeing what others come up with.

Richard