First and foremost : http://www.agrimoney.com/ http://halocommodities.us/market-commentary If you are lazy( or focused on the screen ) and want to listen instead : http://www.agweb.com/market-rally/ Otherwise DTN feed is great, but not free.
Even if there's an incredible source of fundamental news I cannot see you, I, or the other guy knowing something that a big commercial won't already know and have priced into the market already. In the situations where they aren't it becomes a binary event based on news or crop reports etc so might as well just completely go off price.
Wild ride, but got out at flat today. Sold 372.00 on Sep; was long 2x Oct 415 puts - sold those for 22.50, up from 12.875.