One of my senior cats LOVES lettuce but it has to be fresh and the right cut. It can't be a bum end, and there's some mysterious threshold for freshness. Once he gets it he guards it with his life and chows down; then asks for more.
Had a farm cat once that was nuts about raw potato and cucumber. No other foodstuff, but any whiff of those and she'd be right there too take them off your hands.
I found out one of mine has a thing for flour tortillas one day after I had just bought a fresh 10 pack, left it still sealed on the counter and a few hours later, found she had nom'd her way through the plastic bag and ate a huge chunk out of all 10.
I grow them (cat grass seed mix) for my cat, but honestly she prefers when I pull her some of the crabgrass weeds that come up in my balcony plant pots.
As you're out hiking with your cat, a lettuce, and a vacuum cleaner, you come upon a river blocking the path. On the side of the river, there's a boat that's just big enough for you and one other passenger.
The cat can't be left alone with the lettuce.
The vacuum can't be left alone with the cat.
I take the cat across.
Then return.
Then I take the vaccum across.
I return with the cat.
I take the lettuce across.
Then return.
Pick up the cat, and cross a final time.
My cat will take a chunk out of any bread left on a countertop. He somehow also seems to love garlic and onion flavoured things despite their apparent toxicity. Naturally I won't feed him those but he makes a solid effort to swipe them if I turn away.
We had a cat that would devour watermelon. They'd start pestering us to cut out open as soon as we'd get one, and then they'd eat like half of it. It's a great way for the furball to get their liquids, so I'd get a watermelon a week during their season.
My second cat ever loved soy sauce, his sister French fries from McDonalds and vanilla flavoured protein pudding.
In the current cat generation: the oldest does love to take a bite or two from sourdough bread, and another one likes nutella (which is poison for him; he isn't the smartest one if it wasn't obvious)