It may be necessary for you to obtain permission to use quotes on your greeting cards. It depends on the quote. Some quotes are covered by copyright, others trademark, others are free to use with no legal risk.
You may want to use the "Search" feature at the top of this page. In the "keyword" box, enter "permission to use quotes." There are several posts, mostly from the Copyright section of the forum, that cover this topic rather extensively.
As for your poems, they are already copyrighted once they are created. There is no need to do anything more. However, for your added legal protection, you can
register your copyrighted poems. And the registering of your poems is required before any infringement action can be taken in court against an infringer (ie. someone "steals" your poems for their own use).
You can go to
U.S. Copyright Office for more information on the copyright law, and again, you may wish to review the other posts on this forum that cover quotes and permission to use them.
