I finally ordered a copy of the out-of-print Blue Valentine, by Gwen Schultz. What I remember of the story is that the main character's favorite color is blue, and she makes a blue valentine for her teacher. The main character's classmates deride her for this unconventionality (of course), and much of the narrative involves worry over whether or not the teacher will be pleased. The storyline seems slight, but there must have been some emotional current with which I connected.
February 12, 2012 update: Here is the synopsis of the book.
Here is the doll inspired by the book:
Blue Heart Queen Doll (background trees by The Enchanted Cupboard)