A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Looks like an old wall. I guess that’s it then?
Source Viahorizon
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
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
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
One more updated pattern. Not really carbon fiber, but it’s the most popular pattern, so I’ll give you an extra choice.
Source Atle Mo
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
Prismatic Groovy Concentric Background 4
Source GDJ
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin