Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
Embossed lines and squares with subtle highlights.
Source Alex Parker
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
A seamless background texture of old cardboard.
Source V. Hartikainen
A seamless pattern formed from a square tile based on a jpg on Pixabay. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
A version without colours blended together to give a different look.
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