Many weeks ago I found myself at the kitchen sink (nothing new in that) washing leaves, like you do. This was yet another Christmas project. I was a little late collecting the leaves and will definitely be ready next year.
The leaves then went into the Argos spring/summer catalogue between tissue paper! Then you wait with your fingers crossed that no one picks up the catalogue. We also had to eat a cheese cake so we had a circular plastic disc!
Add in some hot glue. . . .
Next year I will collect more leaves to make it bigger. I also thought if you painted it with PVA glue it would be more glossy.