Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
There are many carbon patterns, but this one is tiny.
Source Designova
Might not be super subtle, but quite original in its form.
Source Alex Smith
Prismatic Polka Dots Mark II No Background
Source GDJ
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
An abstract web texture of a polished blue stone (or does it look more like ice).
Source V. Hartikainen