People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Sharp pixel pattern, just like the good old days.
Source Paridhi
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Prismatic Abstract Geometric Background 4
Source GDJ
Tiny circle waves, almost like the ocean.
Source Sagive
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
Prismatic Geometric Pattern Background 2
Source GDJ
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Prismatic Basic Pattern 2 No Background
Source GDJ
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless texture of worn out "cardboard".
Source V. Hartikainen
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
Geometric triangles seem to be quite hot these days.
Source Pixeden