Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
This is a remix of "geometrical pattern 01".
Source Yamachem
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
This is the remix of an Openclipart clipart called "Maze" uploaded by "any_ono_mous".Thanks.This is a seamless pattern of a maze.
Source Yamachem
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
Abstract Tiled Background Extended 6
Source GDJ
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
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
A seamless pattern formed from miutopia's cakes on a tablecloth.
Source Firkin
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
This white background pattern has a seamless grunge style texture. Here's a white grunge style background pattern. Use it as a tiled background image on web sites or for other purposes.
Source V. Hartikainen
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin