smells are closely tied to memory and emotion. this is most true in rodent brains due to high reliance on smell in general, but in humans it is so closely tied that way because of our distant early mammal ancestors, who were similar to modern rodents.
the psychedelic substance psilocybin allows more free association and flow of ideas is to occur, mainly in the cerebellum thinking portion of the brain. deeper portions of the brain are associated with emotions and memories, and in depression this area is markedly in overdrive, while psilocybin studies showed decreased activity with depressed patients, expressed by an overall relief to them personally.
though since they only studied the depressed at that time, there was no way to determine how it affects non depressed patients. this could affect the usefulness of this idea.
but perhaps, since members of ayahuasca churches have lasting positive effects from such substances, maybe a free association of mind is more easily done after taking dmt. and, if thats the case, perhaps a memory was allowed to associate backwards, so that something (not any one thing, but rather a perspective-instant) could remind you of dmt so well that you can smell it.
i think ive strayed from your topic though :/ you said you smelled it just out of the blue?
happens to me fairly often with the smell of weed, but im in a city where im just likely to run into that smell.
...
WAIT.
i just connected now that, since a recent planning for and consummating an experiance with mushrooms, ive smelled the mushroom smell, like once every couple days... im sure it started after a day-or-3-before test dose, rather than with the larger amount (during the recent eclipse).
and im not sure if im in a city where im likely to run into
that smell. the musky fungus-in-hay smell thats just slightly and uniquely off-kilter.
this was a time-limited phenomena though, as it seems to have not happened for a while. but it rained today, so maybe it may again. darn screwy data!
anyway, that might be another piece of evidence for you?
hope this wasnt a waste of your time
"...Well, I know what the Philosopher's Stone is, the Philosopher's Stone is an off-white smoke-able crystal and it is sitting in the kitchen freezer!"
-paraphrased from Dennis McKenna's account of Terence McKenna's words-