native, weed
photo taken in early may
a common plant native to north america (as well as parts of east asia and europe), yellow woodsorrel has a lot of common names: sourgrass, lemon clover, sheep weed, pickle plant. it is edible - various sources describe the taste as "sour" "sharp" and "tangy." it can be used to make orange or yellow dye. yellow woodsorrel grows happily in both shade and sun and does well in nutritionally-poor and disturbed soil.
its leaves fold up at night and open up again in the mornings, like other members of the oxalis family - my false shamrock, a particularly sturdy houseplant, does the same thing.
yellow woodsorrel is notably fast-growing, difficult to get rid of entirely, and will grow even in the worst soils. if you do any weeding at all, you're gonna be seeing a lot of this guy. it's easy to pull, but just keeps coming back.
yellow woodsorrel blooms from spring all through summer and into october.