Be My Valentine, Charlie Brown(1975)
Linus has grown very fond of his teacher Mrs. Othmar. To prove his point, he buys her a heart-shaped box of chocolates, despite Violet's warning that falling in love with a teacher is not a smart idea. He also has to deal with Sally thinking the box is for her. Meanwhile, Charlie Brown, upset that he did not get any valentines at the annual Valentine's Day party, asks what love is truly about.