A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Prismatic Snowflakes Pattern No Background
Source GDJ
A comeback for you: the popular Escheresque, now in black.
Source Patten
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.
Source V. Hartikainen
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
There are many carbon patterns, but this one is tiny.
Source Designova
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A nice light textile pattern for your kit.
Source N8rx