there is no mention of any move to repeal the unjustified restraint on trade that is the 1958 Onion Futures Act.
Alone among agricultural products, the American onion is banned from the futures markets - its half-century of exclusion the result of market manipulation in 1957-8 by a group of traders who, tragically, have not gone down in history as the Chicago Onion Ring.
Onion lobbyists badgered Congress - led by future president Gerald Ford and future presidential candidate Hubert Humphrey - into closing the onion futures market at the CME. They worked on the theory that this would prevent the eternal bogeyman of short selling, and block a reoccurrence of the price volatility (partly caused by the Onion Ring) which had come close to ruining so many American onion growers.

In fact, the ban created an interesting natural experiment - what effect does a futures market have on underlying price volatility? Until then, looking at this question meant comparing (sorry) apples with oranges; one could study prices from before and after the creation of a futures market, but this meant studying a period in which the entire economy had undergone radical change. It wasn't really possible to say that wheat prices had become less volatile because of a CME wheat futures market, when it might equally well have been due to, say, the development of a national banking system, or the spread of railways.

But the onion ban made it possible to compare like with like, and show that the futures market, if anything, made the spot market more stable - just as one might expect.

The authors of the Great Big Plan seem concerned about the competitiveness of US markets. They should know that Indian brokers are ready to start trading their own NCDEX onion futures. Fortunately, NCDEX is holding off for the moment -

“We have received approval from the Forward Market Commission (FMC) for futures trading in onion, but have decided to stay away,” NCDEX’s managing director, P H Ravikumar said. Onion is highly politicised, Ravikumar said...

The story of the onion futures market is an interesting one. You could read it and draw conclusions about the dangers of kneejerk legislation in the wake of a financial crisis. Or note that market players today seem just as ready to blame short sellers for everything that goes wrong as they were in 1958. Or remark on the vital need for regulators to stop a single player dominating a relatively small commodity market. Or ponder on the fact that, according to CME legend Leo Melamed, it was the onion ban that pushed the CME towards reform and innovation, and eventually sparked the birth of the FX market:

The old crowd had played so many squeezes on onions that the government banned onion trading. I instituted a rule book, with rules enforced. And we had to diversify. We tried scrap steel, shrimp, and potatoes, with little success. Meanwhile, I was reading everything by Milton Friedman, who said fixed exchange rates were over, Bretton Woods was finished. I took the first currency contract to him, and he said, 'Wonderful! Do it!' and his feasibility study made him the godfather to the project."

Or - and this is in fact what I plan to do - you could use the whole story to lead up to some tortuous and juvenile pun about how, if you make laws in a hurry, it's bound to end in tears.