It is a messy craft, just perfect for doing with your kids.
Start by blowing up some water balloons. They are the perfect shape and size for this project.
Using water thinned glue, saturate your string completely. You can do this in a large plastic baggie, but I just did mine in a large bowl. Wrap the string around your balloon until you are satisfied with the coverage. Let it dry overnight.
Once the string is completely dry, take a pin and pop the inside balloon.
Cover the edges of your opening with glue and trim. I choose Ric rac.
Add a bow and some grass.