Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Almost like little fish shells, or dragon skin.
Source Graphiste
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
The image depicts a seamless pattern of pine tree leaves.
Source Yamachem
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A very dark asfalt pattern based off of a photo taken with my iPhone.
Source Atle Mo
Zero CC bark from fur tree tileable texture, photographed and made by me. CC0
Source Sojan Janso
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Psychedelic Geometric Background No Black
Source GDJ
Used a cherry by doctormo to make this seamless pattern
Source Firkin
Love the style on this one, very fresh. Diagonal diamond pattern. Get it?
Source INS
Tile available in Inkscape using shift-alt-i on the selected rectangle
Source Firkin
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
Derived from a drawing in 'Historiske Afhandlinger', Adolf Jorgensen, 1898.
Source Firkin