Looks like one of the liverworts.

I don't know what it is, but it looks VERY COOL!

You are correct. It is a liverwort. Thanks.

From a bit of online research:

"At certain times liverworts develop little umbrella-like structures at the edges of their thalli, called receptacles. Male liverworts produce male receptacles (technically called antheridial receptacles), and of course female liverworts produce female receptacles (archegonial receptacles)."

Kevin

Very neat!

Karen

Interesting plant. I wonder if that would be good in a zone 5/6 rock garden.

Well, there certainly are a few to pick from:

(again, online research - I'm becoming fascinated with these guys)

"Liverworts are considered to be the first plant to make the transition from the sea to land, some 400 million years ago, and share a common ancestry with green algae (Chlorophyta). The Hepatophyta division consists of about 8,500 species found throughout the world from the arctic to the tropics. Although some do grow in dry places and a few are aquatic, most are well adapted to the moist habitats in which they are found."

That's Marchantia polymorpha, perhaps the most common livewort worldwide. It is a bane to some commerical nursery growers when it get into their potted plants.
I agree it is a cool looking plant. However if you are also trying to encourage the moss to grow as well then you will have to move the liverwort outa there as the liverwort will simply cover over the mosses in your picture. They are really neat to grow in a pot or any container with drainage. Just use a soil mix of half sand and half peat moss, get it wet, pull up some of the liverwort and press it into the soil and water with rain, distilled, or r/o water. I believe that they can handle some tap water better than can the mosses.

Here is a link that might be useful: Google Marchantia images

Thanks for the ID.

No, I'm not encouraging anything to grow in this area. In fact it was rather infested with violets, so I nuked the heck out of it with repeated sprayings of round-up over a couple of years. The violets and just about every other green thing were killed off, so it's been barren ground for a while now. Upon closer inspection, I've found many colonies of the liverworts in this area.

I like the idea of growing them in a pot.

Kevin

Wow--this is really interesting. I get a lot of this in poorly drained areas and just keep scuffling it out. Never knew what it was and I'm very grateful for you knowledgeable folks at GW for sharing your photos and info. I'll have more respect for my liverworts in the future.