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
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Dark blue concrete wall with some small dust spots.
Source Atle Mo
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
Background pattern made in "Grunge-Like" style. Available in both SVG and JPG formats. Edit to your needs then click the download button.
Source V. Hartikainen
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert
The image depicts polka dot seamless pattern.
Source Yamachem
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen