A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Geometric Pattern Background
Source GDJ
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
Remixed from a drawing in 'Prehistoric Man: researches into the origin of civilisation in the old and the new world', Daniel Wilson, 1876.
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Prepared mostly as a raster in Paint.net and vectorised.
Source Firkin
This seamless light brown background texture resembles a wallpaper with vertical stripes. One way to use it is as a tiled background on web sites.
Source V. Hartikainen
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
A white version of the very popular linen pattern.
Source Ant Ekşiler
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin