If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Prismatic Groovy Concentric Background 3
Source GDJ
Classic 45-degree pattern, light version.
Source Luke McDonald
A version without colours blended together to give a different look.
Source Firkin
A new take on the black linen pattern. Softer this time.
Source Atle Mo
Black brick wall pattern. Brick your site up!
Source Alex Parker
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
Psychedelic Geometric Background No Black
Source GDJ
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks. https://cloaks.deviantart.com
Source Atle Mo
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A seamless pattern made from the gold Penrose triangle by GDJ and the two remixes
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Polka Dots Mark II 3 No Background
Source GDJ