Shakespeare's Secret, by Elise Broach, 2005

When Hero Netherfield moves into the Murphy diamond house, she has nothing good to look forward to but a new set of sixth-grade classmates likely to obsess over her odd name. But when she meets Miriam Roth, her elderly neighbor, who tells her the secret of the stolen Murphy diamond, and its connection to an Elizabethan nobleman who may have been none other than the pen behind the name of Shakespeare, Hero suddenly has more on her mind than just figuring out why Danny Cordova, the cutest boy in the eigth grade, turns up everywhere she goes. Charming middle-grade history-mystery; strongly recommended.