Why is mayella considered a mockingbird in the book to kill a moking bird?

The mockingbird symbolizes innocence, which at first glance you would not think Mayella was innocent. However she did nothing wrong, unless you consider tempting a black man wrong. Then, Bob beat her for her behavior, similar to killing a mockingbird.---------I would argue that Mayella is not innocent, she lies to the court and blames her fault on the innocent Tom Robinson.