Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
So tiny, just 7 by 7 pixels – but still so sexy. Ah yes.
Source Dmitriy Prodchenko
Traced from a drawing in 'Household Stories from the Collection of the Brothers Grimm', Wilhelm Carl Grimm , 1882.
Source Firkin
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A free seamless background with pink spots.
Source V. Hartikainen
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
Prismatic Groovy Concentric Background 5
Source GDJ
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin