The Humane Farming Association is the country's largest organization for the protection of farm animals. This 501(c)(3) nonprofit fights for animal rights, and against factory farming and slaughterhouse abuse. The HFA website has links to investigations and exposes about animal cruelty, as well as information about what you can do to stop it. There is also a marketplace with books for adults and kids available. Membership to HFA is available with a one-time or recurring donation.