BKrenning

I have seen them. Usually the center is yellow or left open for the background fabric.

Here are some large centered ones that I found:

http://www.freespiritfabric.com/core...139&sw_id=1673
http://threekitchenfairies.typepad.c...-tutorial.html
http://www.modabakeshop.com/2009/10/...our-table.html
http://ajpadilla.com/patterns/quick-...plate-coasters
extremely large center: http://sewn.net.au/TipsTools/Tutoria...denPlates.aspx
http://sewmamasew.com/blog2/2010/04/...ock-sew-along/
http://www.bunnyhilldesigns.com/dyna...ree%20Patterns