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
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
White handmade paper pattern with small bumps.
Source Marquis
An attempt for cleaning up the original image in a few steps.
Source Lazur URH
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
You guessed it – looks a bit like cloth.
Source Peax Webdesign
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Derived from an image that was uploaded to Pixabay by starchim01
Source Firkin
Prismatic Floral Background No Black
Source GDJ
Here's a tile-able wood background image for use in web design.
Source V. Hartikainen
Prismatic Triangular Background Design Mark II 5
Source GDJ
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The image depicts a pattern of regular hexagon.As I made to use it for myself,I want to others to use it.Speaking about the ratio of the image, height : width = 2 : √3(1.732...)Ridiculous to say,I realized later that this image is not honey comb pattern.I have to slide the second row.
Source Yamachem
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous