I can't recommend any "literary circles", and I'm not sure that any of the great writers featured on this site were even aware that they were in "literary circles"... i think that they all just wanted to have fun (it's evident in their work that some had more fun than others)
If you're looking for a challenging contemporary writer, I would recommend Daniel Quinn. His novels "Ishmael" and "The Story of B", are either fiercely loved or fiercely hated because of the controversial implications they have for our culture. Whether you love or hate his stories, they are undeniably thought provoking, and his narrative perspective is refreshing.
Happy reading... if you happen to check him out, let me know what you think!