If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Number 1 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
A version without colours blended together to give a different look.
Source Firkin
A blue gray fabric-like texture for websites. An yet another fabric-like texture. It has subtle vertical and diagonal stripes to it.
Source V. Hartikainen
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. A version of the original with random colors.
Source Firkin
Square design drawn in Paint.net and vectorized in Vector Magic.
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
An alternative colour scheme for the original background.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
A bit of scratched up grayness. Always good.
Source Dmitry