Wheat rose on bargain-buying, while soybeans rose on hopes China could buy US supplies.
Chicago Board Of Trade most active corn was up 0.7% at $4.29-3/4 a bushel at 1105 GMT, having fallen some 2% on Monday.
Wheat rose 0.8% to $4.91-1/4 a bushel and soybeans rose 0.2% to $9.07-3/4 a bushel.
The USDA said on Monday that 57% of US corn was in good to excellent condition, down from 58% last week and below analyst expectations that it would stay at 58%.
"CBOT Corn is being drawn higher by the USDA crop report, however the decline of 1 percentage point in good/excellent ratings is not too much to get excited about and does not indicate a major decline in the state of U.S corn," said Michael Magdovitz, senior agriculture commodities analyst at Rabobank.
"The market is sensitive to any decline in conditions following the late US plantings this year. But recent hot and humid weather in the US has been net positive for corn, having accelerated development, and Chicago remains well off its highs for the year."
Brokerage Allendale added in a note: "Grain markets are higher overnight after yesterday's sell-off on forecasts of cooler weather in the Midwest which eased concerns about crop yield losses."
Some 69% of US winter wheat was harvested, below market expectations of 73% and the five-year average of 79%.
Wheat recently fell below the $5 support level in December contract sparking some bargain buying from consumers, Magdovitz said.
"There have also been some scaling back of harvest forecasts in the EU and Russia, which have clipped the expected volumes available from new harvests, to the eventual benefit of US exports," he said.
The European Union's crop monitoring service MARS on Monday cut its forecast of the EU soft wheat yield this year to 6.04 tonnes per hectare (t/ha) from 6.10 t/ha last month.
The soybean market is awaiting progress in the US-China trade talks, especially confirmation of any new purchasing of US soy by China.
"On soybeans, the rumour mill has been rolling in Chicago following Chinese inquiries. But the market is waiting for concrete signs of Chinese purchases," Magdovitz said.
"China has only bought 75% of US soybeans it committed to at the previous Argentine G20 summit so there is a goodwill deficit here."