The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Remixed from a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
This was formed by distorting an image of a background on Pixabay.
Source Firkin
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. 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
A pattern drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat