A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Sounds like something from World of Warcraft. Has to be good.
Source Tony Kinard
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
A free seamless background with pink spots.
Source V. Hartikainen
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
Prismatic Geometric Pattern Background No Black
Source GDJ
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
Fix side and a seamless pattern formed from circles.
Source SliverKnight
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Sort of reminds me of those old house wallpapers.
Source Tish
Prismatic Rounded Squares Grid 3 No Background
Source GDJ