Farm Fatale
iPF Noob
Tip of the day (how to maximize the amount of bonus items from your fields): Typically you will get a bonus item every 3-4 harvests. Recommended field size is around 16-20 square units. Instead of having a big unique field, keep 3-4 of around 16-20 square units each where you will plant wheat. This means that you will most likely get a bonus item every 2 minutes if you harvest your fields sequentially!
I get an item almost all the time when harvesting the whole field. Or every second time, when harvesting half the field.