Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
One week and it's Easter already. Thought I would revisit the decorated egg contest at inkscape community: http://forum.inkscapecommunity.com/index.php?topic=118.0
Source Lazur URH
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A seamless pattern made from the gold Penrose triangle by GDJ and the two remixes
Source Firkin
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
This one needs to be used in small areas; you can see it repeat.
Source Luca
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
Prismatic Groovy Concentric Background 2
Source GDJ
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
As the original image 's page size is too large for its image size, I remixed it.
Source Yamachem
Can’t believe we don’t have this in the collection already! Slick woven pattern with crisp details.
Source Max Rudberg
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio