Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
A criss-cross pattern similar to one I saw mown into a sports field.
Source Firkin
Just like the black maze, only in light gray. Duh.
Source Peax
A floral background formed from numerous clones of flower 117.
Source Firkin
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
The image depicts a seamless pattern of a fishnet with a plenty of fish.It may be a lucky charm for fishermen.
Source Yamachem
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Background formed from the original with an emboss effect
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
An alternative colour scheme for the original background.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless web texture of "green stone".
Source V. Hartikainen
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin