Might not be super subtle, but quite original in its form.
Source Alex Smith
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic 3D Isometric Tessellation Pattern 6
Source GDJ
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
A free pink background pattern.
Source V. Hartikainen
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
From an image on opengameart.org shared by rubberduck.
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Inspired by the B&O Play, I had to make this pattern.
Source Atle Mo
A very dark asfalt pattern based off of a photo taken with my iPhone.
Source Atle Mo
The name is totally random, but hey, it sounds good.
Source Atle Mo
A repeating graphic with ancient pattern. I came up with this name/title at last minute, so you may find that there is very little of ancientness in this pattern after all.
Source V. Hartikainen
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
Looks as if it's spray painted on the wall. You can be sure that this pattern will seamlessly fill your backgrounds on web pages.
Source V. Hartikainen
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin