Grace Livingston Hill 
Found Treasure [EPUB ebook] 

Effie Martin was humiliated! Lawrence Earle, the football hero, was coming back from college, and all the girls were planning a big picnic for him. She had been planning to go, too—until she overheard the girls saying they didn’t want her along because she was too rough, too much of a tomboy. Well, she’d show them. She could be as much a lady as any of them!
Or could she? Almost immediately Effie found herself caught in a struggle between “acting ladylike” and being herself—a struggle she was afraid of losing. Then suddenly, wonderfully, an act of heroism throws Effie into an extraordinary friendship with the football star himself! And she begins the thrilling journey of becoming a woman who understands strong faith and lasting love.