Why not add Super Rare Items for harvesting crops. These Super harvest would be very rare. Like one in 1000 chance of getting one.
Example of Super harvest we could get:
Cabbage patch Glitch Doll - while harvesting cabbage
Carrot Top Carrot Doll - while harvesting carrots
Super Bear Spinach Doll - While harvesting Spinach
Corn Square Crow Doll - while harvesting corn
Also these dolls would grant us some special gifts when we would play with them.