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
Imagine you zoomed in 1000X on some fabric. But then it turned out to be a skeleton!
Source Angelica
A blue gray fabric-like texture for websites. An yet another fabric-like texture. It has subtle vertical and diagonal stripes to it.
Source V. Hartikainen
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This one needs to be used in small areas; you can see it repeat.
Source Luca
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Produced using the clouds, flames and glass blocks plug-ins in Paint.net and the resulting .PNG vectorised with Vector Magic.
Source Firkin
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO