Pycnanthemum.

The mountain mints are delicious.

And one of them is flowering in my garden.

Let me correct that: one of them was flowering in my garden. It's now all hung up to dry, because there's a lot of tea herb to be had from those flowery branches.

I used to grow Pycnanthemum tenuifolium, too, but that one died, so now I only have Pycnanthemum verticillatum. It's a nice mint-family anti-inflammatory, good for coughs and the like. I've mainly used it to give tea blends a better taste, whenever anti-inflammatories are indicated. Similar tasty anti-inflammatories are hyssop, thyme and licorice.

A quick walk through the eclectics gives this:
In King's, Felter and Lloyd say "diaphoretic, stimulant, antispasmodic, carminative, and tonic", mentioning several mountain mints; they say these plants are especially good for colic and similar gut cramps, but go have a good read of the Felter-Lloyd writeup yourself, it's well worth your time if you have one or the other mountain mint in your garden or in your meadows.

Sayre says "stimulant, tonic, and carminative". Sayre usually stays brief on the lesser known plants.

The US Dispensatory says "popularly used in bowel complaints; its hot infusion is diaphoretic." Diaphoretic means make you sweat, and the USDisp says very little else. For the USDisp to write such a positive little note about a little-known nontoxic herb, that's loud applause, so take it as such, eh? Usually they append such notes with "but has been found of little practical use". Bleh for Remington (of USDisp editorship), says I.

It's a nice little herb, and it's also one of the few that flower this late in the year. And all the ones I've tasted had a taste of sweet peppermint. Yay for the pycnanthemums!