Here we have some sweet plastic sweethearts framing a plastic heart. Judging by their looks, they're probably from the 40s or 50s, although sometimes an older plastic mold will be made for decades. Both of the lovers look a little strange, but as long as they're in love, and that's all that matters. Let's not be superficial.
As far as I can tell, the E. Rosen/Rosbro relationship was that E. Rosen (also known as School House Candy) made the candy and Rosbro Plastics made the whimsical containers. The candy was usually lollypops, jelly beans, or some other hard candy. Both E. Rosen and Rosbro were owned by the Rosen family, so it all appears to be one and the same. They were later purchased by Sherwood Brands, who carried on the tradition by making holiday cards and pops and other holiday novelties, as well as tongue tattoos (coming later to the CWM!).