The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A white version of the very popular linen pattern.
Source Ant Ekşiler
Colorful Floral Background No Black
Source GDJ
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
To get the repeating unit, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
The image depicts a seamless pattern of a tortoise in tortoiseshell (hexagon).
Source Yamachem
Prismatic Polka Dots Mark II No Background
Source GDJ
The tile for this is based on a repeating unit close to a design on Pixabay. It can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
You may use it as is, or modify it as you like.
Source V. Hartikainen
I asked Gjermund if he could make a pattern for us – result!
Source Gjermund Gustavsen
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
White handmade paper pattern with small bumps.
Source Marquis
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
A seamless web texture with illustration of pale color stains on canvas.
Source V. Hartikainen
Prismatic Geometric Pattern Background 2
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein