Mine is lilacs, because there was a lilac bush at the bus stop that I used to wait at with my mom when I was a kid, it was my school bus stop and the public bus stop so we spent a lot of time on that corner and now when I smell lilacs I just immediately feel like a kid again.
Dawn in early Summer, in Nature. It is a mix of Petrichor, really fresh coldish air, wet grass and a hint of flowers.