Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. Version with black background.
Source Firkin
The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Remixed from an image that was uploaded to Pixabay by KirstenStar
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
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
Might not be super subtle, but quite original in its form.
Source Alex Smith
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Geometric triangles seem to be quite hot these days.
Source Pixeden
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Prismatic Polka Dots Mark II No Background
Source GDJ
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem