If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Prismatic Groovy Concentric Background 2
Source GDJ
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Background pattern originally a PNG drawn in Paint.net
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Colour version of the original pattern.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin