Oxalis is the genus for wood sorrels, but without a flower I didn't have enough information for a more certain ID. Maybe Oxalis grandis? A nickname for yellow wood sorrel is "sourgrass," and the tart taste comes from....Oxalic acid! gee I wonder how the genus and the acid got their names. High in vitamin c. Tasty. Wouldn't eat this one it's in front of our dumpster.
