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
Derived from a drawing in 'Historiske Afhandlinger', Adolf Jorgensen, 1898.
Source Firkin
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
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
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Gold Triangular Seamless Pattern No Background
Source GDJ
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel
Prismatic Floral Background No Black
Source GDJ
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Prismatic Chevrons Pattern 5 With Background
Source GDJ
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
A seamless stone-like background for blogs or any other type of websites.
Source V. Hartikainen
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen