non-native, sometimes considered a weed
pictures taken in may (left) and june (right).
also known as "eggs and bacon" and "birdsfoot deervetch", which both sound like fake plant names to me. bird's-foot trefoil is not actually three-leaved nor is it a kind of clover; it just kinda looks like it.
i believe these were planted intentionally at the library, but they were so attention-grabbing that i immediately wanted to take a picture and look them up. it is apparently invasive in ten states, and considered a weed generally, but is still planted intentionally for decor. it's not considered invasive here.
in addition to decoration, it is planted in pastures for grazing and in some areas like the side of the road in order to prevent soil erosion. it can create dense mats that choke out other plants.
bird's-foot trefoil blooms from late may/early june until september.