Common name: Redwood sorrel, Oregon oxalis
Oxalis oregana often reminds people of shamrocks. It is an herbaceous perennial groundcover native to the temperate rainforests of the northern Pacific coast and grows in low-light conditions. It has white or pale pink flowers in early summer.
The leaves are used in salads, as edible decoration or to make a drink similar to lemonade. The green seed capsules can be eaten raw and have a taste similar to rhubarb. The plant is also used in alternative medicines as a diuretic and to treat fever and scurvy.
Oxalis photo under trees by Patrick Clarke
Flower photo by USFWS - Pacific Region, Public domain