Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
From a drawing in 'Cassell's Library of English Literature', Henry Morley, 1883.
Source Firkin
Background pattern originally a PNG drawn in Paint.net
Source Firkin
Zero CC tileable dry grass texture, photographed and made by me. CC0
Source Sojan Janso
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
The image is a remix of "edo pattern-samekomon".I changed the color of dots from black to white and added BG in light-yellow.
Source Yamachem
A pale olive green background with a seamless texture.
Source V. Hartikainen
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
Produced using the clouds, flames and glass blocks plug-ins in Paint.net and the resulting .PNG vectorised with Vector Magic.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A new one called white wall, not by me this time.
Source Yuji Honzawa
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
Spice up your next school project with this icon background.
Source Swetha
Formed by distorting an image on Pixabay that was uploaded by gustavorezende. To get the tile this is based on, select the rectangle in Inkscape and use 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 nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen