Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Black brick wall pattern. Brick your site up!
Source Alex Parker
A seamless pattern the starting point for which was a 'light rays' rendering in Paint.net.
Source Firkin
A pattern derived from part of a fractal rendering in Paint.net.
Source Firkin
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
A seamless marble-like texture colored in light blue.
Source V. Hartikainen
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
A seamlessly tileable pink background texture.
Source V. Hartikainen
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
Black And White Floral Pattern Background from PDP.
Source GDJ
Abstract Ellipses Background Grayscale
Source GDJ
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
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