A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
You know you love wood patterns, so here’s one more.
Source Richard Tabor
Prismatic Hexagonalism Pattern No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
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
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
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
You may use it as is, or modify it as you like.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Hexagonalism Pattern No Background
Source GDJ
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo