A new container of mixed nuts.
I was just about to post:
New tub of sour cream. I love the swirl.
(Cue Twilight Zone music)
Popping the tab on a can of Belhaven Black (Nitrogen capsule injects nitrogen into the beer instead of carbon dioxide. It makes a satisfying pop/hiss sound)
Opening a jar of peanut butter
Opening a fresh set of guitar strings.
New tube of toothpaste
In my younger days - being the first to water ski on a calm mirror finish lake. Same with fresh powder for snow skiing.
Cracking the capsule on a glow stick
I miss opening a fresh can of coffee now that my wife and I have grown lazy and use a pod type coffeemaker.
Same here, but now they’re making them out of a new plastic that doesn’t have that great vinyl aroma 
(or toxic chemicals, I guess, but I still miss the smell.)
New tube of toothpaste.
New jar of jelly, because the top has that smooth shiny surface that lets you scoop out a nice jelly lens.
An orange, when you dig into the peel with your fingernails and get that first spritz of orange oil scent.
Similar to the coroner who liked to crack open a cold one.
No love for the new box of 64 Crayola crayons? That SMELL? I’m going to be 52 in a few weeks and I still love that new box of meticulously sharpened brand new crayons.
Somewhere Poppin’ Fresh is reading this thread and feeling very slighted. 
Vegetable tanned leather, sold by the hide (whole animal skin) - vegetable tan is the kind of leather used for belts, saddles, etc. Or, in my case, leather carving and molding - medieval bags, bottles and stuff like that. As opposed to modern chrome tanned leather, which can’t be carved or molded.
It is a proven scientific fact that the first swipe of pure, unsullied peanut butter is the most delicious.
Thanks! Interesting stuff I didn’t know anything about.
Brand new bag of coffee, brand new box of cocoa powder, and oddly a new bottle of machine oil …
I love when I get new pens that have those little plastic protective balls on the tips that you have to pull off before you can write. Those are so fun to yank off!
They aren’t quite the same any more but opening the cap on an new Magic Marker used to be quite a treat.
popping the cork on a bottle of champagne
Cracking open a new bottle of Johnnie Walker Black Label almost always means I’ve taken a flight very recently and am probably on holiday.
A new Terry Pratchett book.
You’re weird.
Opening up a fresh pint of orange or lime sherbet.
Partly because of the child-inspired thrill of “SHERBERT!”, but also because of the adult satisfaction knowing I am not going to be putting it down until it has been completely and happily consumed.
Homebrew, with a swing-top bottle.
Goes “pop” just like that!
I still love to slit open a brand new LP. That’s a “vinyl record” for you youngsters. Even LPs that have been sealed for 30 years still have the wonderful vinyl-and-ink smell.