Here's an Iris in watercolor on and envelope. It's important to use watercolor envelopes because regular envelopes will wrinkle and break down. They're available at most places where you purchase art supplies.
This card started out differently. I was trying to come up with a new design for a dala horse in pencil but didn't care for the way it was turning out so I decided to watercolor over the main body of the horse.
That didn't help much either but I did feel that it was an improvement.
I'm always writing letters so I feel that it's a great chance to unwind and work on design ideas. Everyone seems to enjoy being part of the design process and it helps keep the mail interesting.