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 simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Prismatic Groovy Concentric Background 5
Source GDJ
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
This is sort of fresh, but still feels a bit old school.
Source Martuchox
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez