Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Floral Background No Black
Source GDJ
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Zero CC tileable wood texture, made by me procedurally in Neo Texture Edit.
Source Sojan Janso
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso
Prismatic Hypnotic Pattern No Background
Source GDJ
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo