I have been using some paper I found that has wildflower seeds embedded (the paper is also from recycled sources) and I use a paper cutter to get it to a certain size then I found a scrapbooking paper punch that is perfect for earwires. I hand-write on the back 'PLANT ME' and have a lil stamp on the front that says Seedlings.
That is good for sending out orders etc. but I need something slightly different for my first upcoming show! I had seen the sticky backed adapters in a catalog, Fire Mountain Gems maybe? Anybody have any experience with those and custom cards?