Grain piles are stacking up at Iowa elevators as farmers continue to bring in corn yields that exceed expectations. Iowa corn yields are expected to average a record 198 bushels per acre this year, shattering the previous mark set last year by 6 bushels, according to the U.S. Department of Agriculture (USDA).

Farmers in some areas happily report they are harvesting their best crop ever as yield monitors consistently run above 200 bushels per acre.

"Things are turning out really well. Everybody is...