From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Sharp pixel pattern, just like the good old days.
Source Paridhi
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
From a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
A free seamless background with pink spots.
Source V. Hartikainen
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
This is the remix of an OCAL clipart called "Rain on Window" uploaded by "pagarmidna".Thanks.This is a seamless pattern of raindrops.
Source Yamachem
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen