Horseherb. It's been there all the time, but the rains this years helped it along.

Here is a link that might be useful: Horseherb, Learn to Love It ...

Then nice thing about Horseherb is it will grow where my grass will not grow so I let it have its way as it does not seem to enjoy growing outside of the shaded area of my yard.

Ahh, yes. Thank you. I've seen this around, but I've never seen it entirely take over half an acre as a sort of ground cover. It is quite attractive and, as long as it isn't very invasive, I'm happy to let it do what it wants to do.

Will cattle, sheep, goat, deer eat this stuff?

I've been reading up about it. The word on it is that deer don't particularly like it but that dogs have been known to find it kind of tasty.

The deer nibble on the horseherb in my yard but I don't see any damage and it grows back more quickly than the landscape plants they eat.

Horseherb does prefer shade, goes dormant in heat and disappears entirely in the winter. During the heat and drought last year it was pretty much a no-show.

Ah, the lovely Horseherb- a real thorn in my St. Augustine lawn's side. This stuff will grow where grass will not, plus, if you make the mistake of mulch mowing over it and then continue mowing over the rest of the yard, it WILL spread. But, it's nice to have green in my largely shaded yard where I can't get grass to grow at all.

I have kept quiet on the horseherb front for awhile, but, sometime soon (hopefully this Fall), I will have a Horseherb digging party at my house. We will be landscaping a large portion of our lawn and anyone who wants this stuff is welcome to come and dig it up for free.

To the extent this horseherb is taking over a creek floodplain behind my house, and to the extent that it crowds out grass (that otherwise needs effort in mowing), that might be a good thing. Does horseherb get tall such that it needs mowing? If it just stays a few inches tall and spreads, I could love it!

No, it doesn't get tall and doesn't need mowing. What you have there is probably it's full height.

Oh, great stuff. Bring it on! I want a horseherb lawn out back in the creek bed, but maybe not in my front yard.

It is great stuff for a back yard with creek. Blooming now with yellow daisy-like flowers and rarely goes into the flower beds. Easy to pull out if it does.

Will go into flower beds if you let it, but yes- is very easy to pull out. Mine has taken root in mulch too. I've let mine get to about 8-10 inches (we had a lot of rain then). You don't have to mow it, but, you can encourage new growth and flowers by "taking a little off the top" every now and then with a mower. Think of it as pruning your horseherb.