Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Medium gray fabric pattern with 45-degree lines going across.
Source Atle Mo
Plywood Web Background background image for use in web design.
Source V. Hartikainen
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
A free web background image with a seamless concrete-like texture and an Indian-red color.
Source V. Hartikainen
A seamlessly tile-able grunge background image.
Source V. Hartikainen
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
Colorful Floral Background 3 No Black
Source GDJ
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Prismatic Groovy Concentric Background 2
Source GDJ
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso
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