Recently, this herb began showing up at the stalls in the Ferry Terminal Farmer's market.
We've bought this herb a few times, based upon the farmer's description of "It's like oregano and mint had a baby." (That's a pretty apt description, if the baby in question is Einstein, or Mozart, or some other prodigy.) Each time we'd purchase it, they would tell me the name, and I'd think, "that's easy enough to recall" and wouldn't bother to write it down, only to discover upon arriving home, that I'd forgotten the name of the dern thing, again. This last time around, I remembered it! (Because I mentally associated it with Nutella.) It's known as "Nepitella,"(Calamintha nepeta) and a search of the internet finds some alternate names for it on menus and in other blogs:
Wild Tuscan Mint
Thousand Flowered Aster
In Tuscan recipes,"mint" often means Nepitella, rather than actual peppermint or spearmint, especially if they involve mushrooms. Like mint, Nepitella has digestive medicinal properties when made into tea, and in medieval times was prescribed for this use. (Also as a de-wormer, to promote sweating (who needs that?) and for insomnia (although whether it was used to give you insomnia, or to relieve it, I don't know. I assume the latter. To give you insomnia, I'd prescribe mushrooms, lots of them.)) It also aids in the digestion of beans.
Nepitella is native to the US, Africa, and Southern Europe, growing wild all over the place, so much so that it is considered a weed by gardeners. Here's a close up so you can identify it if it shows up in your local market at some point: