Here's one that may help some people. It's on renderosity and it's licensed for commercial use. PBR textures meant for games. These guys make some nice ones and this is a free set. You need a free renderosity account to download their free stuff. There's a section specifically for game stuff and merchant resources too. Just be sure if you go looking through their free 3d models, you pay attention to the rights associated with each one. Some are non commercial only. This set is obviously, as stated, commercial use/has an extended license, etc.
Click Here For The Link
isource has a site too with a bunch of free textures. They range from 1080x1080 to 4000+ with smaller 512 versions available for most if you need it. There are a lot of free ones, though it is a site that sells textures too. Just need to sign up for a free account to download the free ones. No cost is associated with that. I confirmed it.
Here's the
link.
(Update) Also, If you didn't know about it, you can check out
textures.com
They have a lot of good stuff and you can download a bunch of free ones per day. Plus they have a different free premium texture every day on the main page.