To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.
Source V. Hartikainen
Luxury pattern, looking like it came right out of Paris.
Source Daniel Beaton
The following orange background pattern resembles a honeycomb.
Source V. Hartikainen
Retro Circles Background 7 No Black
Source GDJ
Medium gray fabric pattern with 45-degree lines going across.
Source Atle Mo
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Prismatic Groovy Concentric Background 3
Source GDJ
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso