The home page says, "The Image Gallery is provided as a complimentary source of high quality digital photographs available from the Agricultural Research Service Information Staff."
Creative Commons Image Sites
These are some sources for images to use within your own projects. While most of these databases are meant to provide freely usable images, please check the exact licensing restrictions carefully.
A CC directory of content licensed under the Creative Commons licenses. Includes Image, Video, Audio, and Text. Always check the exact terms of the license!
Use the advanced search to look for CC content (at the bottom of the search screen). Always check the terms of the license! See the link below for a short tutorial.
Free high resolution digital stock photography for corporate or public use. "The purpose of this site is to provide free image reference material for use in all creative pursuits." There are licensing restrictions -- check them!
"Wikimedia Commons is a media repository that is created and maintained... by volunteers....it provides a central repository for freely licensed photographs, diagrams, animations, music, spoken text, video clips, media of all sorts."