The laws that surround lending practices in the US are complicated. If you want to know your rights and look to make sure that the lenders you are using are in fact doing “business by the books”, here are vital resources to help you research. You can start out on our site reading the page that covers payday loans.
Start out by reading up on the Truth in Lending Act here on Wikipedia. There are good links as footnotes in the bottom of the article and in the “further reading” section after the main article.
To get to the deep legalese of these acts, please see Cornell Law’s clickable catalogue of Regulation Z.