8 by 8 pixels, and just what the title says.
Source pixilated
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
A seamless light gray paper texture with horizontal double lines.
Source V. Hartikainen
8 by 8 pixels, and just what the title says.
Source pixilated
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
He influenced us all. “Don’t be sad because it’s over. Smile because it happened.”
Source Atle Mo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
Prismatic Geometric Pattern Background No Black
Source GDJ
Prismatic Geometric Pattern Background 2
Source GDJ
A free light orange brown wallpaper with vertical stripes designed for use as a tiled background on websites. An yet another background pattern with vertical stripes.
Source V. Hartikainen
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
A dark background pattern/texture of a dimpled metal plate.
Source V. Hartikainen
I’m starting to think I have a concrete wall fetish.
Source Atle Mo
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight