You pick the drawer and a mystery will be revealed.  Each mystery drawer has a minimum value of $30 so you are guarenteed to reveal more than the cost of the drawer.  
 
Examples of revealed mysteries:
 
4 Pearls
5 Pearls
Set of Twin pearls plus 2 or 3 additional pearls
2 Edison Pearls
Pearl Ring Fizzer
Pendant Fizzer
Earring Fizzer
Jewelry Settings 
1 Silver Plated Cages with pearl openings
Mini monster oyster opening