This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
A background tile for web with abstract repeating texture of dark "stone wall".
Source V. Hartikainen
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Dark blue concrete wall with some small dust spots.
Source Atle Mo
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A seamless marble-like texture colored in light blue.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Basic Pattern 2 No Background
Source GDJ
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. Version with black background.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Groovy Concentric Background 5
Source GDJ