Photography
We do often purchase stock photos from professionals at a variety of sites, such as Big Stock though often you can find some great free goodies out there. For Photos the best Commercial Free place to look is Flickr, though you can’t just go there and start looking or it will be impossible to sort through everything that is commercial free and not commercial free. The trick is to utilize the Flickr: Advanced Search option. When on that page navigate to the bottom and locate the “Creative Commons” section and check all the boxes that apply (I usually select them all).
Note that you should still always check the conditions of the photo used as they can have requirements, such as photographer recognition, and they can vary from photo to photo throughout the photographers flickr page.
Textures / Patterns
There are actually quite a lot of websites out there that offer free textures or patterns and also a good amount of sites that sell them. However, I am going to highlight one that is perhaps the most popular out of them and provides a great inventory that can be used for nearly any website – Subtle Patterns.