Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
A seamless texture of an abstract wall colored in shades of light orange brown.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
Number 1 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
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
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
Remixed from an image on Pixabay uploaded by Prawny
Source Firkin