Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
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
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
Prismatic Chevrons Pattern 5 With Background
Source GDJ
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks.
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
The image depicts a seamless pattern which was made using stripe-like things including borders.I used OCAL cliparts called "Blue Greek Key With Lines Border" uploaded by "GR8DAN" and "daisy border" uploaded by "johnny_automatic".Thanks.
Source Yamachem
Pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
Clover with background for St. Patrick's Day. Add to a card with a doily, ribbon, a leprechaun or other embellishments.
Source BAJ
The classic notebook paper with horizontal stripes.
Source Are Sundnes
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Produced using the clouds, flames and glass blocks plug-ins in Paint.net and the resulting .PNG vectorised with Vector Magic.
Source Firkin
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin