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
Farmer could be some sort of fabric pattern, with a hint of green.
Source Fabian Schultz
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Tiny little flowers growing on your screen. Nice, huh?
Source Themes Tube
A bit strange this one, but nice at the same time.
Source Diogo Silva
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
Lovely pattern with splattered vintage speckles.
Source David Pomfret
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
A beautiful dark padded pattern, like an old classic sofa.
Source Chris Baldie
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
Abstract Tiled Background Extended 12
Source GDJ
This is the remix of "Tileable Wave Pattern 2" uploaded by "Arvin61r58".Thanks.I added a wire-mesh fence seamless pattern as a lower layer.
Source Yamachem
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin