Physalis philadelphica Lam.
Family: Solanaceae
Mexican ground-cherry, tomatillo
[Physalis ixocarpa auct. non Brot. ex Hornem.,  more...]
Physalis philadelphica image
from USDA Plants website  
Etymology: Physalis: from the Greek physalis, "a bladder," because of the inflated calyx
Plants: annual forb
Conservation Status: Introduced - rarely escaped
Tomatillo. A native of Mexico, cultivated for its fruit, which is used as a vegetable or for sauces, and rarely escaped to sandy or gravelly ground, especially along roadsides and railroads. First collected in 1870 at Sheboygan