The problem is, it's not "really" copyrighted that way unless you have actually published it somehow. I mean, if I just draft a pattern for a block and mail it to myself and then see an identical one somewhere a year later, I can't claim I have a copyright on it because I came up with it first - I didn't DO anything with it. On all of my class handouts, articles (print and online, etc), I put a copyright date. (c) 2007 Catherine Timmons for Glory Quilts. But honestly, it doesn't really protect me. A sympathetic judge might recognize it as a valid copyright, but a legally registered patent, trademark or copyright (depending on what you are doing) is your only true protection.
Even then, it's expensive and frustrating to try to prove that you have an exclusive right to distribute the idea or pattern. Especially in something like quilts. I recently took a pattern off my website because I got a letter from a pattern company claiming I had "stolen" their pattern. Well, I hadn't. I had drafted it all myself, taught it for at least 6 years, taken all my own pictures and wrote the html page myself. I hadn't even SEEN their pattern. When I did look it up, I saw that mine was much more "developed" anyhow. The writer claimed that my pictures were very similar to ones they had used for a TV show. (Even though my pictures were older than the date of the shows I found online.) But it was easiest for me to just remove it. I have neither the resources or the inclination to fight over it.
Copyright law is very complex. I have pretty much stopped teaching classes with commercial patterns for that reason. It's not worth the bother.