What movie has a guy giving his girlfriend yellow play dough with a cute story about it?

I know the movie is fairly recent. I seem to remember that the guy gave his potential love interest the play dough in a brown lunch bag. I believe that he told the woman that the play dough could be shaped into anything she wanted. Before that, there was a huge story about the inventor of play dough using it, I think, on crops. I seem to remember that the movie was a "chick flick." Please help. Thanks.