First of all, Monsanto didn't come up with hybrids (that's what causes the 2nd generation to not breed true). Some RR stuff will grow just fine second generation, canola, soybeans...but it's against the user contract.

Albert Lea seeds in Minnesota has some non-hybrid stuff if you are looking for corn, etc. As Tactical said, look for the key word "heirloom" and you can find plenty in Gurneys or any of the seed catalogs.