People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Can’t believe we don’t have this in the collection already! Slick woven pattern with crisp details.
Source Max Rudberg
A background tile for web with abstract repeating texture of dark "stone wall".
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Prismatic Groovy Concentric Background 3
Source GDJ
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Prismatic Snowflakes Pattern No Background
Source GDJ
Fix side and a seamless pattern formed from circles.
Source SliverKnight
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective