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
Sounds like something from World of Warcraft. Has to be good.
Source Tony Kinard
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
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
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
No idea what Nistri means, but it’s a crisp little pattern nonetheless.
Source Markus Reiter
The image depicts a seamless pattern which was made using stripe-like things including borders.I used OCAL cliparts called "Blue Greek Key With Lines Border" uploaded by "GR8DAN" and "daisy border" uploaded by "johnny_automatic".Thanks.
Source Yamachem
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Subtle scratches on a light gray background.
Source Andrey Ovcharov
Seamless Green Tile Background
Source V. Hartikainen
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin