I am guessing you don't know when the mandate started.
You are correct. My memory was in error. I went back to the data, and it turns out that what I was referring to was not the first year of the mandate, but the several year period in the early 80's when ethanol usage went up about by about 40x and the price of corn dropped by around 60%.
However, I think my basic point still holds. People state (as fact) that putting corn into our gas tanks causes the price of corn to rise, and therefore drives up the price of other foods. That's a reasonable economic theory. But, looking at the data, I don't see any compelling argument. The price of corn is generally higher today than it was pre-mandate, but then it also jumped up a lot more in the early 70's, which probably had nothing to do with ethanol usage. If ethanol is driving the price of corn higher, what then explains the 50% price drops from 1984-86 (I got a 70mpg moped in 84 and then my first 8mpg gas guzzler in 86?), 1996-1998 (I got a real job in 96, moved out of IA and started driving vehicles that didn't suck?), 2008-2009 (guessing housing bust, not my bad), and 2012-14 (no clue on this one, not even a smart ask quip)?
Could it be that corn prices are higher today due to ethanol usage? Sure. Could it be higher demand from China and India (etc)? Yeah, that too. Any of a million other factors?
I just don't see any compelling evidence that shows that increased use of corn for motor CAUSES increased costs for food. Good theory, but that's it.
https://www.macrotrends.net/2532/corn-prices-historical-chart-data