The smell of vinegar always makes me think of the Pas Easter Egg dyeing kits we used to use as kids. IIRC, you’d drop the little color tablets into cups of vinegar to dissolve them, then dip the eggs in suspended on wire rings.
I like the smell of creosote, especially on a hot summer day. It takes me back to my childhood. For me, walking along the railroad tracks was the best way to experience this.
My first exposure to the aroma of PlayDough (sp?), as well as that one and only taste test, took place when I was about six, so my reactions to the smell and taste were “mmm, must bite” and “blaagh!” respectively. I doubt I even knew the word “chemical” at the time, much less “petrochemical.” That descriptor was added many years later with hindsight.
Spent gunpowder. Chinese New Year in NYC hasn’t been the same since the crackdown ban on firecrackers in Chinatown about 20 years ago.
Plastic doll hair, back in the 60s. I kept dolls I didn’t even like just to sniff their hair.
Sea & Ski suntan lotion. (Lubriderm kind of smelled like it before the formula changed)
The inside of a long-used by seldom-opened china cabinet. The freestanding ones you were forbidden to open but did when no one was around.
Nail polish
Water rides (think Pirates of the Caribbean or a log ride) It’s not quite the same as a swimming pool although I’m sure the chemicals are part of it
Pumpkin guts
There’s a certain paper bag smell that always takes me back to coming home from the hobby shop with some new model airplane stuff.
I remember the smell of my grandparents’ bathroom at their old house. I would go over to their house a lot as kid for Sunday dinner and I very distinctly remember the smell of their one and only bathroom.
Then they passed away and I grew up.
Recently I bought some Gold Bond Medicated Foot powder and when I opened it up, there was the smell of my grandparents’ bathroom. I was shocked at how that simple smell immediately brought back vivid memories of my childhood spent at grandma and grandpa’s house.
Green (original?) Palmolive reminds me very strongly of my childhood because that was the only dish soap my mom used.
I guess you could still recreate this but it’s buried in an onslaught of other, hipper fragrances 
A weird chocolaty smell from my 5th grade classroom. No idea if it was a cleaner, perfume or air freshener.
The musky smell of horses reminds me of taking riding lessons on a 20 year old Appaloosa named Eagle (Soaring Eagle). Also of my late Appaloosa/Mustang named Dusty.
I love the smell of auto parts stores / auto shops. The oily, metallic, paint smell. Between my dad managing an auto parts store, “Helping” my Grandpa build a Model T, one uncle working at Ford and another being a garage mechanic - it’s THE smell of all the males I grew up around.
Aqua Velva = Grandpa, Old Spice = Dad, Estee Lauder = Grandma.
Growing up, we had a cedar closet that contained metal bins of coffee and sugar (mid-70’s, high prices, Mom stocked up). It’s a weird scent that every once in a while I come across and I’m immediately standing at the top of the upstairs stairwell, opening the closet.
Cheap BIC pen ink. Mimeographs and the slightly wet paper smell. Silly Putty.
The first thing that popped in my head were crayons. I’m sure there are many more, but for now … it’s crayons.
The smell of apple cider vinegar always reminds me of my gramma, who used it a lot in her cooking. Every so often I’ll open the bottle and just sniff, just for the memories (I also cook with it, but I don’t cook nearly as much as she did).
For my mom the gardener, it’s the smell of tomato plants. Not the fruit, the plants themselves, like when you rub a leaf between your fingers.
And for my grandfather on the other side, it’s the smell of the electric train set he had in the basement. I don’t know precisely what the source of the smell is, but you often find it around operating electrical equipment. Hot metal, maybe?
Ice cold air and diesel exhaust immediately takes me back to winter in Seoul.
Captain Black tobacco reminds me of my father. He only smoked for a couple of years when I was a kid, but it’s instantaneous.
Cottonwood blooms remind me of Springtime in the Northwest.
Wood smoke makes me think of winter at my grandparents house.
This is the first one I thought of. If I smelled it now I’d immediately be taken back to my grade school days fifty years ago.
The smell of Chapstick lip balm.
It has to be the “plain” one in the black tube.
The smell has not changed since my mother put some on my lips in the early 70’s
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I find the smell of fresh/recently applied blacktop to be evocative.
It takes me back to a summer day when I was 8 years old, walking down a country road with other day campers on the way to the swimming pool.
Mimeographed papers! I started school in the early 80s, and my school still did that. Also miss the weird faint purple the print was, and the odd slippery paper.
Purses: My grandma didn’t smoke, but she had an evocative purse scent, too…Dentyne and Coty face powder and leather and pennies. I can still imagine it, and kind of wish I had a purse that smelled like it.
The way it smelled around the teacher’s lounges back when I was in school. A sweet mix of coffee, cigarettes, and…something, I don’t know what, but like fresh sawdust.
Lumber - the smell of a lumberyard or house under construction. When I was little we used to sneak into the cottages that were being built by the lake. That smell transports me.