Wheat is rising the most in four weeks on concern that frost damaged the crop in Argentina.
A smaller harvest in Argentina would cut the country's exports and reduce the global supply of the grain.
Wheat rose 12.25 cents, or 1.9 percent, to $6.7050 a bushel. That was the biggest increase since Aug. 26.
Soybeans and corn also rose.
In metals trading, all major metal prices increased.
Gold logged the biggest gain, climbing $19.90, or 1.5 percent, to $1,336.20 an ounce, its first rise in four days.
In energy trading, oil fell for a fifth straight day after the Energy Department reported an unexpected increase in U.S. oil and gasoline supplies. Oil dropped 47 cents to settle at $102.66 a barrel. That's the lowest closing price since July 3.