How to create a pattern using random displacement like in the photo

I would like to create a surface with a similar texture to the ring I have attached. Is there a way to create a pattern similar over a 2 dimensional plane? I have attached a file with what I have started with.  I can get a random pattern on one of my linear arrays, but when I try it on the second one it only does whole rows at a time. I am open to suggestions on other methods to accomplish this as well. Thanks for any ideas.
-Daniel

ring-texture2.jpg

Sphere-Surface.gh