Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.
Source Eady
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
We have some linen patterns here, but none that are stressed. Until now.
Source Jordan Pittman
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Seamless Prismatic Geometric Pattern With Background
Source GDJ
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
Black brick wall pattern. Brick your site up!
Source Alex Parker
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Here's a bluish gray striped background pattern for use on web sites.
Source V. Hartikainen
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
The image depicts polka dot seamless pattern.
Source Yamachem
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin