Mentuccia is used for both Calamintha and Mentha species including Calamintha ascendens (mentuccia ascendente) and Calamintha nepeta (mentuccia commune), Mentha pulegium (pennyroyal) and sometimes also Mentha longifolia (horse mint). Apart from Italian mint these herbs are referred to as Roman mint. They are on sale everywhere.

Janus

I have been looking for it too. White Flower Farm sells Calaminta nepeta nepeta, I'm just not sure it's the mentuccia I remember from Roman cuisine.

I found it! Well Sweep Farm in Port Murray, NJ. One of the folks there had lived in Italy and knew exactly what I was looking for. They have it listed as 'Nepitella' one of the other Italian names for it. It is Calaminta nepeta.

Here is a link that might be useful: Well Sweep Farm

I had it for 28 years, grown from seeds I picked in my former property near Rome. Never thought of saving seeds which were plentiful and last year's winter here in the northeast did them in along with bay leafs and rosemary. The latter two I can buy anywhere but the mentuccia which I used in all my sauces and stewing I cannot find anywhere. My favorite use of the mentuccia was to use it in Roman Artichokes which of course calls for mentuccia. Should have, could have but was too comfortable having every year.

I'll be curious to see if it comes back after this past winter, but there may be some seeds on the plants.

Here is a small family seed company that carries it: https://www.quailseeds.com/store/p305/Mentuccia_Romana.html