CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.
Source Firkin
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A seamless pattern based on a tile that can be achieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin