Two things always made me think of adulthood when I was a kid: Coffee and Car Keys.
I always loved holding the keys in my hand after returning from some car visit I was sent to by relatives. It made me feel adult, as if I was actually the one driving. I think mentally I associated it with adulthood because every time adults came around they had car keys in their hand! Or maybe it was because it gave them the freedom to come and go. In any event, I came to hold my head up a little higher whenever I could walk around with those keys.
Coffee also reminded me of adulthood. It seemed that it was something that only grown-ups were allowed to do. If they weren’t drinking coffee they were drinking liquor lol. All this represented adulthood for me.
Feel free to list some of the things that reminded you of adulthood when you were a kid.