Vintage teen girl doll underwear setfrom the 1940s, maybe 1950s  -- bra and panties. Pretty floral print on a white taffeta-like background (not sure what the actual material is).
 
Appears to be new, old-store-stock. My photos show some shelf patina, but high-pixel camera shows it exaggerated. The set is crisp and like new. The bra closes at the back with a button, and the panties have good stretch at the waist.
 
Measurements:
Bra -- 5" across laid flat at bottom
Panties -- 4.5" waist to crotch; 3" waist laid flat unstretched; 5" waist when stretched laid flat