The green leaflets are sensitive and will often fold together when touched, hence the common names sensitive plant or sleeping plant.
The uniquely structured foliage is a favored food of the Cloudless Sulphur caterpillar and the white-tailed deer.
Another of our ubiquitous waste place weeds, flourishing in disturbed areas, along roadsides and railways;
When the glorious blossoms yield to winter's chill, the bountiful seeds provide a boon for the bobwhite quail - the "partridge" and the pea.
Fabaceae (Pea Family). Chamaecrista fasciculata (also Cassia). Native to the Southeastern U.S.
These lovely individuals (and hundreds of their friends) live along my daily route around town. Perhaps there are a few in your neighborhood as well...