These images are done on envelopes and are to be sent to the Prison Library Projects annual Postmarked exhibition.
Here is some information about the project:
For many years, inmates from around the country wrote to the Prison Library Project and we were amazed by the amazing artwork that accompanied requests for books. These beautiful illustrations were our inspiration for a mail art exhibition and fundraiser. Postmarked was developed seven years ago for the Claremont Forum's Prison Library Project, which sends books free to prisoners in the U.S. upon their request. Providing education and opportunity to learn about mail art, view new and established mail artists' works, and to participate in the experience of creating and sending mail art. Now in its 7th year, this exhibition is one of the largest in California.
and here is the projects official blog: