I made a little catnip mouse out of felt and added a heart for extra cuteness.
All you do is fold the felt and cut out a taco shape. Whip stitch the top and leave an opening in the back. Stuff in stuffing and catnip. I added a tail made of braided embroidery thread and sewed it closed. Then all you have to do is cut out ear shapes and sew on and make little knots for the eyes. Easy, quick and cute. I have a big tub of catnip from the pet store for $3, I can make a ton of these critters for my friends with cats.
p.s. make sure you sew everything securely so the cats don't eat the parts.