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
I love the movie Pineapple Express, and I’m also liking this Pineapple right here.
Source Audee Mirza
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Alternative colour scheme for the original floral pattern.
Source Firkin
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
Classic vertical lines, in all its subtlety.
Source Cody L
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
Lovely light gray floral motif with some subtle shades.
Source GraphicsWall
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
A gray background pattern with a texture of textile. Suits perfectly for web design.
Source V. Hartikainen