A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Zero CC tileable moss or lichen covered stone texture, edited from pixabay. CC0
Source Sojan Janso
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
A bit of scratched up grayness. Always good.
Source Dmitry
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Orange-red pattern for tiled backgrounds.
Source V. Hartikainen
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
A seamless background colored in pale orange. It has a paper like texture with diagonal grid pattern.
Source V. Hartikainen
This is a seamless pattern of a woody texture.The original image is here:https://pixabay.com/ja/users/ClassicallyPrinted-1302233/
Source Yamachem
A bit of scratched up grayness. Always good.
Source Dmitry
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Derived from an image that was uploaded to Pixabay by darkmoon1968
Source Firkin
Background formed from the original with an emboss effect
Source GDJ
A background tile for web with abstract repeating texture of dark "stone wall".
Source V. Hartikainen
Black & white version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
A version without colours blended together to give a different look.
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
Here's a new gray "fabric" pattern. Use it as backgrounds for websites or for other purposes.
Source V. Hartikainen
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim