A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
Remixed from a JPG that was uploaded to Pixabay by Osckar
Source Firkin
A light gray background pattern with seamless fabric-like texture and almost unnoticeable stripes.
Source V. Hartikainen
Psychedelic Geometric Background No Black
Source GDJ
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
Prismatic Abstract Line Art Pattern Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Tiny little flowers growing on your screen. Nice, huh?
Source Themes Tube
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
This is the remix of an OCAL clipart called "Art Nouveau ornament" uploaded by "microcosme".Thanks.This is a seamless pattern of an Art Nouveau ornament.
Source Yamachem
Prismatic Snowflakes Pattern No Background
Source GDJ
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A very slick dark rubber grip pattern, sort of like the grip on a camera.
Source Sinisha
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin