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
Colour version of the original seamless pattern.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
Different from the original in being a simple tile stored as a pattern definition, rather than numerous repeated objects. Hence easy and quick to give this pattern to objects of different shapes. To get the tile in Inkscape, select the rectangle and use shift+alt+i.
Source Firkin
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A nice and simple white rotated tile pattern.
Source Another One
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
I’m guessing this is related to the Sony Vaio? It’s a nice pattern no matter where it’s from.
Source Zigzain
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Sometimes you just need the simplest thing.
Source Fabricio
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
Prismatic Groovy Concentric Background 3 No Black
Source GDJ