Inspired by a couple of other threads here.
Broccoli. I’d starve before I’d eat it. Now, I love it and eat some almost every day. Also, almost anything that is good for you.
Eggs. Brushing my teeth. Wearing glasses.
Avocado, Brushing my teeth, Long car rides.
Tomatoes. Despised them as a child. Then one day, when I was about 20 or so, I had a weird craving for a tuna sandwich with lettuce and tomato. I spent a week thinking about it and tried it, and decided that tomatoes weren’t all that bad. I now happily eat tomatoes and wish I wasn’t such a lousy gardener so I could have my own red ripe homegrown tomatoes for sandwiches.
Steamed shrimp. Couldn’t even stand the smell as a kid; now, there isn’t a big enough bowlful – outta my way!
Avocado is #1 for me. My parents were in the clean plate club so I used to swallow pieces of avocado like pills. Then in my early twenties, I had sushi for the first time with that little piece of avocado in it and mind=blown. Love them! Never did learn to like my other “swallow like a pill food” which was green peppers though.
Eggs were also not my favorite and I still can’t deal with very yolky versions of egg dishes, especially deviled eggs, but I do love eggs benedict now and some scrambled eggs with veggies & cheese.
Sweet potatoes. They don’t have to involve marshmallows.
I read the first word as “tornadoes” and got as far as the whole snip I quoted before I realized “something is wrong here” and backed up to discover my error.
Oops on me!
The fact that despite living in tornado-free Los Angeles the very idea of tornadoes terrified me as a little kid may have had something to do with this reading error. Maybe. Carry on. 
I thought tomatoes were tasty even when I was little.
'Zactly Sweet potatoes themselves are fine. The nasty sugar bomb casserole is not. I wasn’t exactly a kid or an adult when I figured this out, but it was still a revelation when I realized they were two radically different forms of the same basic ingredient.
As to me:
Brussels sprouts. Nasty hateful inedible things when I was a kid. Now they’re darn good. Not quite “I love 'em”, but close. To be fair, a lot of selective breeding effort in the last 40 years has gone into making less nasty bitter cultivars of sprouts. Which efforts have paid off.
Coffee. Disgusting stuff when I was a kid and even in college I had no use for it. Pretty quickly in USAF I learned to love even Folgers. Nowadays it’s mostly good Central / South American stuff for me. But every day has a bunch, and happily so.
Laying down in bed and going to sleep
I found a new appreciation for all the cruciferous vegetables after I moved out of my parents’ house and realized there were ways of preparing them other than boiling them to a foul-smelling, flavorless mush.
Lotta people have had that revelation. I personally wasn’t exposed to it until I got married & met my MIL. But yeah, that treatment can take the freshest most wonderful [whatever] and convert it into inedible bitter mush.
Asparagus. It was pretty expensive so it didn’t get served very often which was just fine with me. To me it was like eating grass. Not sure where I turned the corner on it but I now love asparagus, pretty much any way it can be cooked… even eat it raw.
This and so many other foods. Mushrooms. Spinich. Beans. Mainly, texture was an issue for me. I love textures now. I still don’t care for bananas though.
All colors. I had favorites and those I hated, but how silly of me. They are all beautiful.
Certain musical instruments and types of music. I’m never going to love all organ music, but some of it is great.
I won’t use the word “love”, but I really like Pepsi Zero Sugar and growing up, I hated all diet soda. I don’t think Pepsi Zero Sugar is the world’s greatest drink, but I like it quite a bit and I think it really just is the formula they use for it, which has changed over the years, but remains good.
Anyway, I can also drink Coke Zero.
Both are also really good in their cherry variety, though not vanilla or anything, which always tastes kind of disgusting.
Classical music
Fish, unless it was breaded, formed into little sticks and smothered in tartar sauce. I now love all kinds of freshly made wild caught fish and eat it whenever I can. The closes I come to fish sticks is fried perch or walleye, which is hard to find prepared correctly, even in SE Michigan. I love cedar plank salmon, grilled swordfish and tuna, can’t get enough. Under 14 year old me was disgusted with fish like these. And lobster and crab looked like big bugs, who woujld eat big bugs? Turns out that I do and love them.
Naps.
Seriously. I never wanted to nap or go to sleep when I was little but now a good nap on a lazy afternoon is one of life’s greatest joys.
Also have to agree with fresh tomatoes. I always liked tomato-based things like pasta sauce, ketchup, salsa, etc but wouldn’t touch a fresh one. It drove my dad crazy since he was a big gardener and grew a ton every year. I was in my 20s before I tried one again and suddenly discovered the beauty that is a truly fresh tomato from the garden. Hate I missed out on them all those years.
Sour cream. It grossed me out and made me gag as a kid. Now I love it on baked potatoes, beef stroganoff, mexican dishes, and elsewhere.
Sauteed spinach. Wouldn’t touch it as a kid, now I love to cook it up, using butter AND olive oil, garlic, salt, lemon. a divine veggie.
Mushrooms. I violently rejected them until my mid 20’s. Now I love 'em in oh so many ways.
Liverwurst. 10 year old me: Worst than liver? No thanks!
25 year old me: Please put thick, giant slabs of it in my sandwich, thanks.
It’s gotta be good liverwurst though. I do NOT like bologna and supermarket deli liverwurst tastes like mushy bologna.
Oh man! No better sandwich imaginable than liverwurst, red onion, and mustard.