I have a small white pill with a 5 with a box around it, what is it?

Its listed as Busprione, an anxiety drug that is prescribed due to lower chances of addiction than other anxiety meds.

In any case if it's not yours don't take it, dispose of it asap as it can be quite dangerous since these drugs affect the brain directly.

Buspirone - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Buspirone)