Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden
Here's a dark background pattern that contains a steel grid pattern as a texture. Use it as a website background or for other purposes. It's free!
Source V. Hartikainen
Sort of reminds me of those old house wallpapers.
Source Tish
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
Medium gray pattern with small strokes to give a weave effect.
Source Catherine
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
The name is totally random, but hey, it sounds good.
Source Atle Mo
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857
Source Firkin
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
This was formed by distorting an image of a background on Pixabay.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A seamless pattern formed from a tile made from page ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin