Ranunculus repens
Creeping Buttercup (Ranunculus repens) is a herbaceous flowering plant of the genus Ranunculus.
Like other buttercups, it is toxic when fresh (but not after haying and drying). This fact, along with its invasive nature, has made it a problem plant in pastures. Livestock avoid eating it. The only way to get rid of it is by hand-pulling or selective weeding of an invaded lawn.()