The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.
Source Eady
A very dark asfalt pattern based off of a photo taken with my iPhone.
Source Atle Mo
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Used a cherry by doctormo to make this seamless pattern
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Non-seamless pattern drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Black brick wall pattern. Brick your site up!
Source Alex Parker
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
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
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Abstract Tiled Background Extended 10
Source GDJ
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous