The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen
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
Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
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
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
A beautiful dark padded pattern, like an old classic sofa.
Source Chris Baldie
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle 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
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
Black brick wall pattern. Brick your site up!
Source Alex Parker
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen