Continuing the geometric trend, here is one more.
Source Mike Warner
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
Psychedelic Geometric Background No Black
Source GDJ
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
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
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Derived from a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton