Stitch Talk #4 Double Circles

This week's Stitch Talk is more circles!  Double circles, a circle within a circle.  

I made this starting with one circle, then stitching another inside it.

Backtrack a bit to start the next circle, if necessary.  Stitch that circle, but when putting the one inside it, locate it such that it's not right across from the other one.
 

Continue on, filling in the space.

For fun, I kept the inner circles across from each other, and come up with an interesting vine.  Reminds me of something growing in the ocean.