I can think of several cross stitch patterns that could be enlarged and used for a pillow design. Cartoon characters with simple line art like those pictured would probably be best. Winne the Pooh, Hello Kitty, etc.
We have one of these and someone put a piece of a popsicle stick and wrote "Rock Concert" - Love Rock Art.Garden Trinkets - Awesome Ideas, Projects and Tutorials! Including, from 'instructables', this creative 'garden thing' project with rocks.