Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Retro Circles Background 5 No Black
Source GDJ
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Orange-red pattern for tiled backgrounds.
Source V. Hartikainen
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
Zero CC tileable grass texture, photographed and made by me. CC0
Source Sojan Janso
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
A seamless pattern created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
Colour version of the original pattern.
Source Firkin
White little knobs, coming in at 10x10px. Sweet!
Source Amos
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Prismatic Hexagonalism Pattern No Background
Source GDJ
Tile-able Dark Brown Wood Background. Feel free to use it as a background image in your designs or somewhere on the web. By the way, the color seems to be close to Coffee Brown.
Source V. Hartikainen
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin