Silkworm and I found this tutorial at our favorite nature crafts blog (mentioned prior when we made our felt shooting star), Twig and Toadstool! I can't count the times we've made use of it. Every time we mosey around outside and spot leaves on the ground, I have to stop to make myself a crown, and if there are ever any small enough leaves, I make one for Silkworm, too.
It's pretty easy peasy. Just take it one leaf at a time. Break the stem off without damaging the leaf and use it to add the next leaf (poke it through to the back and then poke it back up). Once you've got a circle big enough to fit on your head, close it with one last stem. If one layer of leaves isn't enough, you can bulk it up by simply stitching more leaves onto the base leaves of your crown. When it's all well and finished, shake it off a bit to get rid of any bugs, and then crown yourself or somebody special. Proceed into the woods to hold a ceremony for the new woodland prince or princess.