From the Tx. A & M web site:
“Yellow woodsorrel (Oxalis stricta), also commonly called oxalis or sheep sorrel, is a spring or summer annual weed throughout the south, mid-west and eastern states. Yellow woodsorrel is a problem weed found in lawns as well as in ornamental plantings. In lawns, the weed develops a creeping growth habit often rooting at the nodes of low growing stems. In ornamental beds or gardens the plant develops an upright or bushy growth habit.
Description. Yellow woodsorrel leaves are divided into 3 heart-shaped leaflets, green to purplish in color, with long petioles attached to a weak, branching stem. Stems may be prostrate or erect up to 50 cm tall. Plants have a taproot, but some species spread by weak rhizomes.
Flowers of yellow woodsorrel have 5 bright yellow petals and are about 2 cm wide. Flowers develop in clusters in an unequally branched umbel. Seed develops in a slender capsule 5 to 15 mm long with 5 ridges and a pointed tip. Mature seed scatter several feet when the capsule bursts."
From the UT Native Plant database:
“A low spreading plant with clover-like, sour-tasting leaves and 1 to several yellow flowers.
With their clover-like leaves, the wood sorrels are easy to recognize. The sour taste of the leaves is distinctive and they may be used in salads, but sparingly, because of the oxalic acid content. The genus name comes from the Greek oxys (sour). This species is a cosmopolitan weed, perhaps originally native to North America. It is especially common as a garden weed. The very similar Upright Yellow Wood Sorrel (O. dillenii), a European introduction, has seed capsules on reflexed stalks. Large Yellow Wood Sorrel (O. grandis) has flowers to 1 (2.5 cm) wide and leaves often with purple edges; it is native and grows from Indiana east to Pennsylvania and south to Georgia and Louisiana.
Use Food: EDIBLE PARTS: Small amounts of leaves, flowers, seeds, tubers/roots eaten raw are not dangerous. Gather stems and leaves during early spring through fall. Tender stems and leaves can be steeped in hot water. Use liquid as a sour lemonade-type drink. For tea, use a handful of leaves per pint of water. Add to salads for a lemony taste. Cook with greens to enhance mild flavors. Remove stems if too stringy. Use flowers raw in salads or as cooked greens. Add young seed pods to salads or cook with the leaves and stems. Clean tubers and roots and eat raw or cooked with the greens, seeds, and flowers. (Poisonous Plants of N.C.)
Warning: POISONOUS PARTS: All parts. Low toxicity if ingested (no documented cases in humans). Symptoms in grazing animals, when eaten in large quantities, may cause trembling, cramps, and staggering as in grazing animals. Toxic Principle: Soluble oxalate.
Deer Resistant: High "