Not those. The flowers are tiny, sort of like baby's breath. The plant comes up fairly early in the season, grows fairly quickly, but doesn't flower until mid to late summer. Plants were established when we moved in the house so I don't have any other info about them.

Sorrel perhaps?

I think you have hit it spot on! Looked up ajuga pics and ours seem to be the 'metallica' with blue/purple flowers (altho we rarely allow them to reach flowering height...they mostly stay "mowed"). It's still a weed as far as we are concerned. Trying to grow grass and this stuff takes over. Very invasive. If we find a mature plant during the weeding process (the only way we have found effective so far, but are looking for a chemical method) you'll dig up five or six runners shooting out a foot in all directions. Funny thing...one store was selling these at $4 ea....and they were out of stock! Anyway, now that I know the name, will look into specific ways to stop the hordes. If you know any would appreciate hearing it. Thanks for the help!

Mint family has square stems. You can note that by rolling them between finger and thumb - kinda like a pencil, 'cept pencils aren't usually square. I'm thinking that you've discovered a catnip plant. Lots of those in older neighborhoods where I live but I'm not in Colorado. Fragrance is kinda minty and not unpleasant. Catnip makes darn good herb tea. Plantladyco is talking about mint family plants with licorice fragrance. How 'bout that? I'm not really familiar with hyssop altho' agastache is sometimes called anise hyssop and I've had that for years. I suppose there's a chance that it's monarda but I wouldn't really think so. And there are just "tons" of mints including calamintha and other nepeta. Seems like calamintha has a rather strange eucaplyptus-like smell (bell not quite ringing). Anyway, try google images. Steve Here is a link that might be useful: catnip