Sagina subulata.

Or one of the other Pearlworts, depending on where you live.

The odds-on favorite for zone 7 in this country is Sagina decumbens. Sagina saginoides, another common Pearlwort, is found in the western third of the US. Your plant seems most like S. decumbens to me.

Yes: one of the common weedy species.

Hello and thank you all very much! I just love this ID site. :-) jekeesl, di you mean to say Sagina procumbens instead of Sagina decumbens? The reason I say that is that, from looking all this up, decumens is an annual, and also seems to grow more upright than the one I have, which grows more like a mat. Let me know what you think.

When I first saw Sagina here, I had a difficult time determining ID. There seems to be a fine line between "matted" and "clumped". I finally read that S. decumbens typically has flowers with 5 petals, and S. procumbens flowers usually have 4. So my plant was probably S. decumbens and yours seems similar in general appearance. However, species is indeterminent, for me, from your photos. Maybe you can check your plant's petal count with a magnifying lens.

If you do review the Sagina key from the following link, you can click on any of the species listed to see a more detailed description.

Here is a link that might be useful: FNA Sagina key

Alexa, forgot to mention that I had checked BONAP maps earlier (see link). Sagina procumbens is considered more of a northern species, so S. decumbens seemed more likely.

Here is a link that might be useful: Sagina distribution