Inspired by a pattern found in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
CC0 and seamless wellington boot pattern.
Source SliverKnight
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
A seamless background of warped stripes on paper.
Source V. Hartikainen
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Textured Red Brown Plastic, Free Background Pattern. Although there's already enough plastic in our lives, let's bring it to the web too.)
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Wasn't satisfied with the original's colouring. Too much component transfer and colormatrixes yet the results are lacking a bit. So this time it is a simple black to transparent fade, making it possible remixing easily once there will be other blending modes supported as well. Probably in inkscape 0.92.
Source Lazur URH
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Found on the ground in french cafe in kunming, Yunnan, china
Source Rejon