You can't send them directly yourself, but they can be shipped...
Locate the state, then the city or county where you think they are being held.
Any book received by an inmate must be shipped directly from a trusted commercial source such as Barnes and Noble or Amazon. Further, for safety purposes, the book must be a paperback version.
To locate an inmate or arrestee, or to find out more about the book policies for your jail or prison, begin searching here: