Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Zero CC tileable brick texture, 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
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
This light background pattern has a texture of "frozen" surface with diagonal stripes. Here's an yet another addition to the collection of free website backgrounds.
Source V. Hartikainen
A repeating background with a look of paper. I have added some changes to PatCreator. Now you can share your designs by submitting them to a new gallery section. Start by clicking Edit with PatCreator above.
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Retro Circles Background 8 No Black
Source GDJ
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Zero CC tileable wood texture, made by me procedurally in Neo Texture Edit.
Source Sojan Janso
Heavily remixed from a drawing in 'Barbara Leybourne; a story of eighty years ago', Sarah Hamer, 1889.
Source Firkin
A classic dark tile for a bit of vintage darkness.
Source Listvetra