Wheat futures soared 5 percent as dry weather in the U.S. brought worries that the crop wouldn't be nearly as large as traders had expected.
Reports of a drought in Russia also had traders anticipating tighter supplies of wheat. The July contract settled up 30.25 cents at $6.3875. Corn also rose, 4 percent.
Oil and gold futures fell to their lowest levels in months as the dollar continued to march higher against the euro. Traders have been buying dollars aggressively over the past two weeks because they're nervous that Greece might be forced to exit the euro bloc.
Dollar-priced commodities like oil and gold tend to fall when the dollar rises. Crude is at the lowest level since November, and gold is the lowest since December.