A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
From a drawing of the coat of arms of the Ottoman Empire on Wikimedia.
Source Firkin
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
A bit strange this one, but nice at the same time.
Source Diogo Silva
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
I’m starting to think I have a concrete wall fetish.
Source Atle Mo
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
From a drawing in 'Kingsdene', Maria Fetherstonehaugh, 1878.
Source Firkin
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Background pattern originally a PNG drawn in Paint.net
Source Firkin