I subbed for the Primary at the last minute for Emilee and the lesson was Joseph Smith receives the plates. The message was if you're obedient, you are blessed, but I got my idea from when Angel Moroni showed Joseph the plates, but then he had to wait 4 years to take the plates from Hill Cumorah - so I let the girls each open the lid to their own treasure (chocolates) but didn't let them take them home with them. They had to give the chocolates back to me. Based on their reaction, I'd say it was effective ;)
I made 6 chocolates for each of them and labeled them appropriately to what Joseph Smith saw in the buried box on Hill Cumorah:
