The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
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 pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
This light blue background pattern is quite pleasing to the eye, it consists of a tiny rough grid pattern, which is seamless by design. That's it, if you like the color, you can use this seamless pattern in a web design without making any further modifications to it.
Source V. Hartikainen
Submitted in a cream color, but you know how I like it.
Source Devin Holmes
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
This metal background pattern resembles a metal plate with rivets. Solid rivets on a metal plate.
Source V. Hartikainen
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Abstract Tiled Background Extended 12
Source GDJ
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
Prismatic Abstract Geometric Background 4
Source GDJ
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Submitted in a cream color, but you know how I like it.
Source Devin Holmes