People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
Here's a quite bright pink background pattern for use on websites. It doesn't look like a real fur, but it definitely resembles one.
Source V. Hartikainen
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The image is the remix of "wire-mesh fence seamless pattern" .This is a more minute version of it.Sorry for the file size.Using path>difference in Inkscape, I will cut out any silhouette from this pattern and create a "meshed silhouette".
Source Yamachem
Sharp but soft triangles in light shades of gray.
Source Pixeden
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This is the remix of "Strawberry Pattern Background" uploaded by "GDJ". Thanks. I realigned strawberries so as to get seamless and changed the BG color.
Source Yamachem
A dark metal plate with an embossed grid pattern and a bit of rust. Here's a dark metal plate texture for use as a tiled background on web pages.
Source V. Hartikainen
A version without colours blended together to give a different look.
Source Firkin
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
Tweed is back in style – you heard it here first. Also, the @2X version here is great!
Source Simon Leo
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
This yellow background consists of a pattern of glossy gold buttons arranged in polka dot style on a seamless texture. Here's a pale yellow background pattern. Feel free to use it for your needs!
Source V. Hartikainen