Jan you have so many great insights on how it works here! You always do!
Judi - I started fooling around with the two blocks you suggested - Snowball and Jack in the Pulpit.
First I substituted Jack in the Pulpit for Goose in the Pond in my pattern shown in above post. You get a similar secondary circle effect with a lot less piecing.
Loved the results!
Then I tried it with the Snowball block in two different versions. I hope I chose the right type of snowball block. It too came out really neat. (Please pardon the hasty color and border choices)
Rootyr, I thought you might like to see them too: