It is one of the fleabanes. Problem with telling which is which is the leaves vary so much. You can have 10 plants in a small area and each will have different shapes and sizes of leaves. The only real way to tell which is for it to send up it's flower stalk.

Sorrels, other than the human family name, are Rumex species and some are considered invasice weeds, Sheep Sorrel, while others are grown as salad ingrediants, French Sorrel. Some can be somewhat toxic, ie the Sheep Sorrels, while others, ie. French sorrel, are a good food source. All do have the same, or at least a similar, root system, one that sends runners everywhere and all can be invasive.