Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Metal. Squared style.
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Lovely pattern with some good-looking non-random noise lines.
From a drawing in 'Line and form', Walter Crane, 1914.
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Incoming catena. Stone & well. CC0 texture.
Lovely pattern with splattered vintage speckles.
Source David Pomfret
A pattern formed from repeated instances of corner decoration 8. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
You can never get enough of these tiny pixel patterns with sharp lines.
Black brick wall pattern. Brick your site up!
Source Alex Parker
Prismatic Snowflakes Pattern 3 No Background
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Colorful Floral Background No Black
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Gamedev - Wood Textures. CC0 License.
Source Davit Masia
Floral background 16 (colour)
CC0 textures, backgrounds.
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
Metal-Rusty. CC0 License.
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
The image depicts a Japanese Edo pattern called "kanoko or 鹿の子" meaning "fawn" which has a fur with small white spots.
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf