Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Prismatic Floral Background No Black
Source GDJ
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
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
This ons is quite old school looking. Retro, even. I like it.
Source Arno Declercq
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
White circles connecting on a light gray background.
Source Mark Collins
Retro Circles Background 8 No Black
Source GDJ
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
Some dark 45 degree angles creating a nice pattern. Huge.
Source Dark Sharp Edges
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
Geometric triangles seem to be quite hot these days.
Source Pixeden