Straw into Gold by Carol Beth Anderson

Years ago, Pel fell for a gorgeous Faerie . . . and enslaved herself to him in the process. Now, she’s making the best of it by using borrowed Fae magic to render herself invisible and steal from the wealthy at court. While she’s there, a handsome human man named Cole is arrested when his father claims he can spin straw into gold. Intrigued, Pel follows Cole into his cell. When she learns he has no such talent, she offers to help, if he’ll pay for her assistance. But a little help isn’t enough. The king demands he spin more and more straw into gold. Pel has grown attached to Cole’s generous heart and wants to truly protect him. But to do so, she’ll have to ask him for his firstborn.
If she does that, Cole will never trust her again. And if she doesn’t . . . the king will take his life. Is it possible to find both love and freedom?