Where can a 15 year old get a small loan
Parental consent. Most states won't allow it unless the teen as a steady job and/or is emancipated
Parent, brother, sister
This is where Grandma's and Grandpa's come in. Make your business case.
You can try at http://vinzpayday.me/.
If you are only 15 years old, there is no way that you can get a loan. Even if you visit http://www.paydayloanservices.me/ you won't find anything there. Loans are given to people who are 18 years old and above.