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
From a drawing in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
As the original image 's page size is too large for its image size, I remixed it.
Source Yamachem
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
CC0 and seamless wellington boot pattern.
Source SliverKnight
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
Prismatic Groovy Concentric Background 4
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
A version without colours blended together to give a different look.
Source Firkin
Nicely executed tiling for an interesting pattern.
Source Ignasi Àvila Padró
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Abstract Tiled Background Extended 12
Source GDJ
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen