Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
I have no idea how to describe this one, but it’s light and delicate.
Source JBasoo
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
A pale olive green background with a seamless texture.
Source V. Hartikainen
A bit of scratched up grayness. Always good.
Source Dmitry
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
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
A web texture of brown canvas. Will look great, when used in dark web designs.
Source V. Hartikainen
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
This is the remix of "Colorful Floral Pattern Background 3" uploaded by "GDJ". Thanks.
Source Yamachem
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
He influenced us all. “Don’t be sad because it’s over. Smile because it happened.”
Source Atle Mo
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Remixed from a raster on Pixabay, that was uploaded by ArtsyBee.
Source Firkin
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 seamless paper background texture colored in pale yellow. This seamless texture is ideal for those who need a yellow background image for their website. The texture resembles paper.
Source V. Hartikainen
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Seamless pattern inspired by a drawing on Pixabay. To get the tile this is formed from, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin