Not really. what you are thinking about is a wild green, such as poke sallet.

Poke is good only in the spring, before the plant has flowered. It is one of the first green plants available in the spring. It can be quite bitter, and is a diuretic and can be a powerful pergative. Note I write "sallet" NOT 'SALAD'. Sallet is a term for a green fresh spring tonic.

Randall and I have eaten poke - I use the same recipe, but I boil it first for about 3 minutes, then rinse. This gets rid of some of the alcaloids that make poke bitter. You can also add sugar, honey, or molasses.

Chard is very domesticated. Unless you happen to be around an old field where some was grown and let bolt (go to seed) and then grew on a volunteer basis. Not very likely, but could happen.

You can find it in grocery stores and farmers markets. Go either to HEB or if Austin has a Central Market, they should have some.