A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Inspired by this, I came up with this pattern. Madness!
Source Atle Mo
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A light gray background pattern with seamless fabric-like texture and almost unnoticeable stripes.
Source V. Hartikainen
ZeroCC tileable wood boards texture, 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
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
Zero CC tileable hard cover red book, scanned and made by me. CC0
Source Sojan Janso
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
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
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Colourful background achieved with gradient fills.
Source Firkin