This invasive, edible, water-loving, creeping plant inhabits a large portion of my backyard and is impossible to eradicate from the yard. DollarWeed grows year-round here in Lehigh. It's bright green leaves are up to 2 inches in diameter and round with scalloped edges. The stem attaches to the leaf in the center of the leaf. Where the stem meets the leaf there are veins on the leaf that extend outward.
If the stem attaches at the edge of a kidney-shaped leaf, this is not DollarWeed, it is Dichondra carolinensis (Carolina Dichondra or Ponyfoot).
If there is a red spot in the center of the leaves, this is not DollarWeed, it is Marsh Pennywort (Hydrocotyle ranunculoides).
View the video here. http://www.youtube.com/watch?v=0xNIPdbU_WM&
It grows under everything and arises back up on the other side of rocks, raised beds, and edging. Dig underneath this plant and discover a maze of white runners with white roots every few inches. Every little piece of the runner and it's roots must be pulled out of the ground or it grows back. I read somewhere that the only way to get rid of it is to move. This not being an option for most of us, we can still get back at this plant in a couple of ways. We can embrace this bold plant and change our perception of what a weed is and/or we can EAT IT.
DollarWeed tastes like parsley to me and contains many vitamins and minerals. As in most greens, the smaller ones are more tender than the larger leaves. Throw some leaves in a salad, use as a garnish as you would parsley, add it to soups, or top deviled eggs with it. Google "pennywort recipe" for other ideas including teas juice, and drinks.