There have been times when key memories have been triggered by my own senses. Usually these memories are about emotionally-charged or traumatic events.
Scents, for example, include the original, classic scent of Old Spice, which reminds me of seeing my Dad getting ready for work in the mornings; and the smell of burning scrub reminds me of the day my home burned to the ground in 1986.
The beautiful name necklace on this site, however, brings back the wonderful memory of Dad returning home in 1976 from six month deployment in Egypt with a beautiful silver name necklace for me. I loved that necklace.