Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
This background texture resembles stone. It may be used as a background on web pages or on some of their html elements (header, borders, menu bar, etc.). Just modify it for your needs.
Source V. Hartikainen
A seamless pattern formed from miutopia mug remixes on a tablecloth.
Source Firkin
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
Inspired by a pattern found in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A very slick dark rubber grip pattern, sort of like the grip on a camera.
Source Sinisha
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Seamless Olive Green Web Background Image
Source V. Hartikainen
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
Here's an yet another background for websites, with a seamless texture of wood planks this time.
Source V. Hartikainen
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin