Heirloom Knitting has some really intricate patterns...There are a couple free ones if you follow the link on the left:http://www.heirloom-knitting.co.uk/heirloom_knitting.html
Wendy Engstrom has a beautiful pattern-not specifically a 'wedding ring' type lace shawl. http://www.fiberholics.com/lace.html
I think the wedding ring shawls refer to the shawls ability to be passed through the ring, rather than a specific pattern.
This would depend more on the yarn weight and the lace pattern used.