View photos of edible and medicinal plant Berberis trifoliolata [Mahonia trifoliolata] (Algerita), profiled in Medicinal Plants of the American Southwest and Wild Edible Plants of Texas.

A passage from Medicinal Plants of the American Southwest:

Although bitter, it makes an effective gargle for bacterial–derived pharyngitis. The nasal wash or repeated gargle is a sound treatment for sinusitis as well. Combined with internal use (along with Echinacea or Myrrh) its upper–respiratory cold–fighting power should not be underestimated.

A passage from Wild Edible Plants of Texas:

Pleasant and refreshing, the berries can be eaten directly from the bush, prepared as a jam/jelly, or dried for later use. Most American Indians in the area utilized the berries as a seasonal–supplemental food.