Oh, great thread! Here are some of mine; I'm sure I'll think of others after I post:
raspberry Kool-Aid takes me back to childhood summer days
Old Spice immediately makes me think of my late father
real grapes reminds me of picking grapes with my parents and then my Mom would make & can grape jelly
charcoal takes me back to my Dad grilling burgers, and also sometimes Girl Scout camping trips
egg nog is like Christmas morning opening stockings (that's why it's my favorite Philosophy body wash!)
violets remind me of my college days because I was a sorority girl and one of my big sisters gave me a bottle of violet cologne (our sorority flower) -- to this day I love violet-scented things!
Downy takes me back to childhood and freshly-dried sheets & towels after a hot bath
Oh, I agree on the new crayon smell....it's the first day of school all over again!
Smells can trigger bad memories too, unfortunately; the smell of smoke (not just wood smoke, but the certain smell of burning building materials which goes beyond wood smoke smell) makes me freeze with terror because I remember our apartment fire in 1999 and escaping from a burning building. But we survived and things are good, so I don't dwell on that anymore.
Someone else keep this thread going!