People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Prismatic Hexagonalist Pattern No Background
Source GDJ
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
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
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
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
Seamless Olive Green Web Background Image
Source V. Hartikainen
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This is a hot one. Small, sharp and unique.
Source GraphicsWall
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The image depicts a seamless pattern which was made using stripe-like things including borders.I used OCAL cliparts called "Blue Greek Key With Lines Border" uploaded by "GR8DAN" and "daisy border" uploaded by "johnny_automatic".Thanks.
Source Yamachem
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous