Alternative colour scheme. 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
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
Spice up your next school project with this icon background.
Source Swetha
This is a remix of "geometrical pattern 01".
Source Yamachem
Prismatic Triangular Background Design Mark II 5
Source GDJ
Retro Circles Background 5 No Black
Source GDJ
Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
Light gray version of the Binding pattern that looks a bit like fabric.
Source Newbury
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin