Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
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
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Cassell's Library of English Literature', Henry Morley, 1883.
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
You may use it as is, or modify it as you like.
Source V. Hartikainen
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From drawing in 'Musings in Maoriland', Thomas Bracken, 1890.
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ