The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
The following orange background pattern resembles a honeycomb.
Source V. Hartikainen
From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
Green Web Background, Seamless tile.
Source V. Hartikainen
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
As the original image 's page size is too large for its image size, I remixed it.
Source Yamachem
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A free web background image with a seamless concrete-like texture and an Indian-red color.
Source V. Hartikainen
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
If you need a green background for your blog/website, try this one. Remember that Green Striped Background is seamlessly tileable.
Source V. Hartikainen
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
A pattern formed from a photograph of a 16th century ceramic tile.
Source Firkin
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso