From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
The image is a remix of "edo pattern-samekomon".I changed the color of dots from black to white and added BG in light-yellow.
Source Yamachem
Number five from the same submitter, makes my job easy.
Source Dima Shiper
ZeroCC tileable wood boards texture, photographed and made by me. CC0
Source Sojan Janso
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
Green Background Pattern
Source V. Hartikainen
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo