I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
Colorful Floral Background 3 No Black
Source GDJ
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
Gold Triangular Seamless Pattern No Background
Source GDJ
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
Sounds like something from World of Warcraft. Has to be good.
Source Tony Kinard
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
A comeback for you: the popular Escheresque, now in black.
Source Patten
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A white version of the very popular linen pattern.
Source Ant Ekşiler
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight