Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
Lovely pattern with splattered vintage speckles.
Source David Pomfret
It’s big, it’s gradient—and it’s square.
Source Brankic1979
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
Lovely light gray floral motif with some subtle shades.
Source GraphicsWall
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
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
I’m not going to lie – if you submit something with the words Norwegian and Rose in it, it’s likely I’ll publish it.
Source Fredrik Scheide
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Remixed from a drawing in 'Kulturgeschichte der Deutschen im Mittelalter' Franz von Loeher, 1891. The unit tile can be had by selecting the rectangle in Inkscape and using shift-alt-i
Source Firkin
A seamless stone-like background for blogs or any other type of websites.
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A dark metallic background with a pattern of stamped dots. Here's a dark "metallic" background pattern for you.
Source V. Hartikainen
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel