Original minus the background
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
Luxury pattern, looking like it came right out of Paris.
Source Daniel Beaton
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
From an image on opengameart.org shared by rubberduck.
Source Firkin
Seamless Prismatic Quadrilateral Line Art Pattern No Background
Source GDJ
The tile can be had by selecting the rectangle in Inkscape and using shift+alt+i. Remixed from a drawing in 'Flowers of Song', Frederick Weatherly, 1895.
Source Firkin
You were craving more leather, so I whipped this up by scanning a leather jacket.
Source Atle Mo
Medium gray fabric pattern with 45-degree lines going across.
Source Atle Mo
CC0 and seamless wellington boot pattern.
Source SliverKnight
A seamless marble-like texture colored in light blue.
Source V. Hartikainen
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
A tile-able background for websites with paper-like texture and a grid pattern layered on top of it.
Source V. Hartikainen
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
A seamlessly tileable pink background texture.
Source V. Hartikainen
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
A background pattern with wavy green vertical stripes. This one has green stripes on a white background. Download if you like it.
Source V. Hartikainen
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
Here's an yet another seamless note paper texture for use as a background on websites.
Source V. Hartikainen
From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
Zero CC tileable dry grass texture, photographed and made by me. CC0
Source Sojan Janso