The stay flat envelopes work really well. I love all of your personal birdie touches. I made the mistake of ordering 'Do Not Bend' stickers for mine which added an extra cost for me and extra weight to the envelopes. A handmade stamp is so much smarter! :)
I love seeing your work ready to head out in the mail. I purchased 3 of your prints about a month ago and LOVE, LOVE, LOVE them (have them arranged together in a single frame with a 3-opening matte.) I still have the envelope they were mailed in (and the little postcard you enclosed.) LOVE it ALL!
I'm planning to purchase another print (the polar bear and bird) for a dear friend of mine who is a bird-watcher and went to Canada to see the polar bear migration. She will ADORE that print of yours!