Soybeans rose after recent sharp declines, largely caused by the US-China trade war, created buying opportunities.
Chicago Board of Trade most-active wheat was down 1.1 percent at $5.21-1/4 a bushel at 1052 GMT. Corn fell 0.2 percent to $3.59-1/2 a bushel, soybeans rose 0.5 percent to $8.45-3/4 a bushel.
The USDA said after Monday's market close that 16 percent of US corn was harvested by Sunday, the same as analysts' expectations and against 11 percent this time last year.
Some 28 percent of US winter wheat was planted against analysts' expectations of 25 percent and 26 percent last year.
"The USDA gave a positive picture of US corn and wheat in its crop progress report late on Monday which is weakening markets today," said Charles Clack, agricultural commodity analyst at Rabobank.
"The USDA said US corn harvesting is progressing well, faster than last year at 16 percent finished. A very large US corn crop is expected and although there is still a long way to go, we are not seeing new fear factors today. This large US corn crop is likely to continue hanging over the market."
"US winter wheat planting is also making positive progress and is faster than last year. A lot more work remains but the picture today is that generally things are going well. There is no reason for immediate concern."
Soybeans rose despite the continuing trade war between the US and China, which buys 60 percent of the oilseed traded worldwide. US soybean exports to China have almost stopped since July when Beijing imposed heavy tariffs on US imports
"The trade war between the United States and China is escalating, which is causing worries that it will have a longer term impact on US soybean exports," said Phin Ziebell, an agribusiness economist at National Australia Bank.
"US exporters will have a tough time selling that record crop which is currently being harvested."
But buying interest was supporting.
"The bearish factors remain in soybeans, with the US/China trade war continuing and the US harvest progress positive," Rabobank's Clack said.
"But with prices so low, some may take this as a buying opportunity in soybeans with still only a small part of the US soybean crop completed and a lot of weather disruption still possible."