Three academics at U of Illinois examine some issues of the Market Facilitation Program. As they say at one point, the questionable legality of the program is academic, because Congress didn't challenge it when they gave the Commodity Credit Corporation more money.
A history of CCC would be interesting. It was created under the New Deal, following examples from WWI and the Hoover administration of using government corporations to gain administrative flexibility, particularly IMO to evade the requirement for yearly appropriation bills passed by Congress.
USDA bureaucrats during my time used it creatively. The administrative people used CCC authorities to go around the Government Printing Office rules to get fast printing of forms and directives when we were implementing new legislation and disaster programs.
In 1983 IIRC the Reagan administration used it for a disaster program for Texas counties which was part of a deal to get conservative Texas Democrats (which used to exist) in the House to vote for legislation.
Also in 1983 there was the Payment-in-Kind program, which used creative lawyering to transform CCC loan collateral into payments for farmers to divert acreage from production.
As computers came along, the procurement and IT people used CCC financing for computer equipment, setting off a 10-15 year battle with the Congress which ended with Congress tightening the restrictions on ASCS/FSA buying of computers.
After I retired there were further special programs authorized--I think by both the Bush and Obama administrations, but I don't remember the specifics.