I had also thought about stitching more circular background around them (even bargello) and making kissing balls to hang or to just sit on the dining table and on side tables for the "season."
Anyway, I have already given you a tutorial on drawing circles onto canvas - you can find these under the label "canvas preparation." This first circle is 3 1/8" diameter, and is good for inserting the smaller one (the moon) to make a small ornament. Actually, 3 1/2" would be better, but I can't find my drawing, and I'm too lazy right now to do another.
The second scan is the small circle, 2 3/8" diameter, that I use for the "moon" on the napkin rings. To insert it into the larger circle, draw the big one FIRST, mark the centers lightly, and then count up 21 threads from the horizontal center and make a mark to begin the top of the smaller circle. These center marks can be easily dotted out with white acrylic paint.
And now the new motifs! I had to give the bat green eyes, and the witch has a silver hat band and an orange scarf. I had intended just a black silhouette against the yellow/orange moon, but couldn't resist a bit of color here.
Enjoy! - and see what you can come up with for further decoration.