8 by 8 pixels, and just what the title says.
Source pixilated
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Abstract Tiled Background Extended 6
Source GDJ
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
A version without colours blended together to give a different look.
Source Firkin
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A seamless pattern the starting point for which was a 'light rays' rendering in Paint.net.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
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
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
This metal background pattern resembles a metal plate with rivets. Solid rivets on a metal plate.
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin