If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
Black brick wall pattern. Brick your site up!
Source Alex Parker
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
A bit of scratched up grayness. Always good.
Source Dmitry
A seamless pattern created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
There are many carbon patterns, but this one is tiny.
Source Designova
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin