Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using 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
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
A seamless web texture of "green stone".
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by darkmoon1968
Source Firkin
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Otis Ray Redding was an American soul singer-songwriter, record producer, arranger, and talent scout. So you know.
Source Thomas Myrman
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
Can’t believe we don’t have this in the collection already! Slick woven pattern with crisp details.
Source Max Rudberg
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion