From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
Zero CC bark from fur tree tileable texture, photographed and made by me. CC0
Source Sojan Janso
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
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
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Redrawn based on a drawing in 'По Сѣверо-Западу Россіи' Konstantin Sluchevsky, 1897.
Source Firkin
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks.
An abstract web texture of a polished blue stone (or does it look more like ice).
Source V. Hartikainen
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Prismatic Triangular Background Design Mark II 5
Source GDJ
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso