Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
A free pink background pattern.
Source V. Hartikainen
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Inspired by a design found in 'Konstantinápolyi emlékeim', Miklos Chriszto, 1893.
Source Firkin
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.
Source V. Hartikainen
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
Derived from an image that was uploaded to Pixabay by pugmom40
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter