Garden sorrel. The garden or sheep sorrel (Rumex acetosa) grows in meadows, by streams & woodlands, preferring an acidic soil. It can be used as a dye, silver polish & a stain remover. Medicinally it promotes urine formation (diuretic) and is used to treat kidney disorders. It is also used both in cooking and as a salad leaf. Large quantities should be avoided due to its high level of oxalic acid, which can cause mineral deficiencies.