People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
A beautiful dark padded pattern, like an old classic sofa.
Source Chris Baldie
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Inspired by this, I came up with this pattern. Madness!
Source Atle Mo
If you want png files of thisu can download them here :
Source Viscious-Speed
Abstract Tiled Background Extended 12
Source GDJ
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
To get the tile this is formed from select the rectangle in Inkscape and use 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