I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee
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 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
Might not be super subtle, but quite original in its form.
Source Alex Smith
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i
Source Firkin
I’m guessing this is related to the Sony Vaio? It’s a nice pattern no matter where it’s from.
Source Zigzain
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
Prismatic Hexagonalism Pattern No Background
Source GDJ
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Same as gray sand but lighter. A sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Remixed from a JPG that was uploaded to Pixabay by Osckar
Source Firkin
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Prismatic Abstract Background Design No Black
Source GDJ
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Background pattern originally a PNG drawn in Paint.net
Source Firkin
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Sort of like the Photoshop transparent background, but better!
Source Alex Parker