View photos of the edible plant, Oxalis pes-caprae (African wood sorrel), profiled in the Wild Edible Series: Arizona.

A passage from Wild Edible Plants of Arizona:

The leaves, flowers, and green seed pods of all Sorrel species are edible. They are best eaten raw (in small to
moderate amounts), added to salads or used as a sandwich garnish for their tart–sour taste.