Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
One more updated pattern. Not really carbon fiber, but it’s the most popular pattern, so I’ll give you an extra choice.
Source Atle Mo
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
Derived from an image that was uploaded to Pixabay by darkmoon1968
Source Firkin
Sometimes you just need the simplest thing.
Source Fabricio
Prismatic Abstract Geometric Background 4
Source GDJ
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern
Source Firkin
Looks like an old wall. I guess that’s it then?
Source Viahorizon
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
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
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
Here's an yet another background for websites, with a seamless texture of wood planks this time.
Source V. Hartikainen
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin