Press leaves on a hard surface covered with wax paper. Place a flat object or pan on top and weigh it down with cans or anything heavy.
Start covering the pumpkin by spreading mod podge on the backs of the leaves and placing them along the bottom of the pumpkin all around.
Make a ring of additional leaves around the stem.
Allow the leaves to set up for a little while maybe 20-30 minutes.
Then coat the entire leaf area with additional mod podge to seal and protect.
Notes
The leaves used here are from Ninebark 'Diablo', Weigela 'Wine and Roses' shrubs. However, you can use any leaves you like including colorful fall leaves you've collected.