Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
Psychedelic Geometric Background No Black
Source GDJ
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
Some dark 45 degree angles creating a nice pattern. Huge.
Source Dark Sharp Edges
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Prismatic Floral Background No Black
Source GDJ
It’s an egg, in the form of a pattern. This really is 2012.
Source Paul Phönixweiß
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
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
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
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Light gray version of the Binding pattern that looks a bit like fabric.
Source Newbury
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers