What is wrong with buying a car back from the insurance company after they have totaled it?  That's pretty much standard procedure.   The insurance company doesn't want it. 

Crop insurance is the same deal.  They come out and adjust the crop.  They tell you what they think it is worth.  You have a choice of taking what they pay (the guarantee minus what they say is in the field), or of harvesting it for grain and using the actual yield as the value which they do not have to pay.     If you harvest for grain, you must offset the actual yield against the guarantee....essentially the grain from the field belongs to the insurance company, up until the amount they guarantee it to make....  If you take their adjustment yield, the field is yours to do with as you please with the exception that you cannot harvest it for grain.  There is nothing fraudulent about grazing or baling it after it has been adjusted, that is completely according to the rules.