An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Prismatic Polka Dots Mark II No Background
Source GDJ
There are many carbon patterns, but this one is tiny.
Source Designova
Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin
A seamless background pattern with a texture of wood planks. This wood background pattern has vertically arranged planks. You may try to rotate it 90°, to see how it will look like when the wood planks are arranged horizontally.
Source V. Hartikainen
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
A seamless background of warped stripes on paper.
Source V. Hartikainen
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
Kaleidoscope Prismatic Abstract No Background
Source GDJ
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Prismatic Hexagonalism Pattern No Background
Source GDJ
Prismatic Triangular Background Design Mark II 5
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Psychedelic Geometric Background No Black
Source GDJ
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin