This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Sort of like the back of a wooden board. Light, subtle, and stylish, just the way we like it!
Source Nikolalek
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
White circles connecting on a light gray background.
Source Mark Collins
A seamless background tile of aged paper with shabby look.
Source V. Hartikainen
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The image is a design of blue glass.How about using it as background image?
Source Yamachem
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.
Source Firkin
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc