O.K., this trauma is a weird one.
I remember a sci-fi movie (from the ’60s or ’70s) where people would stand before a ruler or monarch and if they were found guilty, the floor would open and they would fall into a pit occupied by what looked like a huge bunch of cabbage leaves (reddish leaves, if my memory serves me right.) When they fell in they would scream and basically be eaten by the giant mass of cabbage. The idea a being eaten by a cabbage patch somehow terrified me beyond all measure. To this day I have an irrational hatred of salad. No joke.
Also, I believe their civilization might have lived underground, but I can’t say for sure. It’s a weird one, but I STILL have nightmares about it. Perhaps confronting that cabbage while eating some coleslaw, a little corned-beef and a giant hot-dog with sauerkraut will free me from this cruciferous cage.
UPDATE: NAME THAT TRAUMA SOLVED! Special thanks to reader Tim Tylor who lettuce know the answer with THE LOST CONTINENT!