A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
This one is amazing, truly original. Go use it!
Source Viahorizon
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
Derived from a drawing in 'Elfrica. An historical romance of the twelfth century', Charlotte Boger, 1885
Source Firkin
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
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
A dark striped seamless pattern suitable for use as a background on websites.
Source V. Hartikainen
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
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
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Abstract Ellipses Background Grayscale
Source GDJ
An aged paper background tile with smeared and pressed text.
Source V. Hartikainen
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
An alternative colour scheme to the original seamless pattern.
Source Firkin
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
A light brushed aluminum pattern for your pleasure.
Source Tim Ward