Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
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
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Colour version of the original pattern inspired by the front cover of 'Old and New Paris', Henry Edwards, 1894.
Source Firkin
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
Prismatic Abstract Background Design
Source GDJ
Prismatic Geometric Pattern Background
Source GDJ
Seamless Green Tile Background
Source V. Hartikainen
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Here's a quite bright pink background pattern for use on websites. It doesn't look like a real fur, but it definitely resembles one.
Source V. Hartikainen