Might not be super subtle, but quite original in its form.
Source Alex Smith
The image depicts a Japanese Edo pattern called "kanoko or 鹿の子" meaning "fawn" which has a fur with small white spots.
Source Yamachem
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A free web background image with a seamless concrete-like texture and an Indian-red color.
Source V. Hartikainen
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Similar to original, but without gaps in between the arrows. This seamless pattern was created from a rectangular tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This is a hot one. Small, sharp and unique.
Source GraphicsWall
Tile-able Dark Brown Wood Background. Feel free to use it as a background image in your designs or somewhere on the web. By the way, the color seems to be close to Coffee Brown.
Source V. Hartikainen
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
A dark background pattern/texture of a dimpled metal plate.
Source V. Hartikainen
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
A background pattern with blue on white vertical stripes.
Source V. Hartikainen
Pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen