Many commodities altered course through the day as investors reassessed ideas of what the death of Osama Bin Laden meant for asset values.
Indeed, there was some thought of a reprisal attack by Islamic militants.
"There is little doubt that the north western Corn Belt areas will plant more corn this week than was originally anticipated and that has certainly provided some of the pressure," Darrell Holaday at Country Futures said.
Rival broker US Commodities said: "This weather this morning provides an open window for the northern Plains and western Corn Belt." The eastern Corn Belt "also looks drier this morning versus the weekend forecast".
To sum up, the week should enable "aggressive planting in all of the western Corn Belt, north half of Illinois, northern Ohio and northern Indiana", with the area from the Ohio Valley to the Mississippi Delta "stalled".
So while the planting pace as of Sunday, to be revealed in US Department of Agriculture data, will be well below the 40% average by now, with the market estimating a figure of 15-16%, there is a real chance of catch-up , which was what the market traded on Monday.
Indeed, while months often begin with a bout of buying from funds flush with fresh cash, not this time.
"While they may have more buying to do, it may not present itself unless the ag markets resume upward momentum," Benson Quinn Commodities said.
In fact, funds were sellers of an estimated 12,000 corn contracts on the day, (along with 2,000 soybean and 1,000 wheat lots).
Chicago's July lot fell 2.9% to $7.34 ½ a bushel, if not shedding all of the gains of the last session, while the new crop December lot fell 1.2% to $6.61 ¼ a bushel.
The grain's performance weighed on
In Kansas, July [hard red winter] wheat ended down 1.3% at $8.90 ½ a bushel, while spring wheat fell 1.1% to $9.37 ½ a bushel in Minneapolis.
"Concern about dry conditions in the hard red winter area along with cold overnight temperatures and wet forecasts for the hard red spring wheat areas prompted a strong early rally in wheat. But when the corn market could not hold gains, the wheat retreated," Mr Holaday said.
US Commodities noted too that soft red winter wheat "will deteriorate on the rain".
Sure, as US Commodities said, "China is basically now out of the US soybean export market. The domestic market will now be the leader".
But this was already known. What is positive for the oilseed is the prospect of decent progress in corn sowings, lowering the chance of growers switching instead to soybeans, which can be planted later.
Among soft commodities,
There was some disappointment, technically, at a weak start, signalling that a recovery on Friday may have been a blip in a downward trend, rather than anything more substantial.
Indeed, Terry Roggensack at Hightower Report had noted talk of "better buying interest from funds early this week, in contrast to the long liquidation selling from last week".
However, he also highlighted "unexpected rains for eastern Texas over the weekend", improving sowing prospects for the parched US cotton-producing state.
Still, volume was thin, on a day when many markets, such as China, Russia, and the UK were closed for a labour day holiday.
And traders failed to reveal any particular spark behind today's rise other than further buying by funds getting into the commodity, for which demand is proving more resilient than demand.
The latest US regulatory data, late on Friday, showed speculators (as included in a broad definition) continuing to increase their net long exposure to cotton n the week to April 26, to some 40,000 lots, from 28,000 lots a month ago.