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
Embossed lines and squares with subtle highlights.
Source Alex Parker
A floral background formed from numerous clones of flower 117.
Source Firkin
Background formed from the original with an emboss effect
Source GDJ
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Remixed from a PNG that was uploaded to Pixabay by VictorianLady
Source Firkin
Prismatic Abstract Line Art Pattern Background
Source GDJ
A white version of the very popular linen pattern.
Source Ant Ekşiler
The tile this is based on was adapted from an image that was uploaded to Pixabay by frolicsomepl. It can be had in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
Abstract Tiled Background Extended 10
Source GDJ
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks.
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ