Creative Commons - Make sure to mark the box to "modify, adapt, or build upon". You can use Creative Commons to search for copyright-free images, videos, and music.
EduPic - Photographs and drawings that are free for you to use
Google Images - To search for copyright-free images, scroll down to Usage Rights and select "Only images labeled for reuse." Enter the subject that you're looking for in the box at the top of the page marked “Find images of…”
Microsoft Office - Free clipart, photos, and animations
Photo Pin - Copyright-free photos for your artistic use
Photos 8 - A great place to find photographs of animals, plants, or landscapes for your projects!
Pics4Learning - Pics4Learning is a copyright-friendly image library for teachers and students. The Pics4Learning collection consists of thousands of images that have been donated by students, teachers, and amateur photographers. Unlike many Internet sites, permission has been granted for teachers and students to use all of the images donated to the Pics4Learning collection.
The World Images Kiosk - Offers more than 75,000 images for teachers and students to use in their academic projects.