A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
U.S.-based National Fire Protection Association standard fire diamond for flagging risks posed by hazardous materials. The red diamond has a number 0-4 depending on flammability. The blue diamond has a number 0-4 depending on health hazard. The yellow has a number 0-4 depending on reactivity. the white square has a special notice, e.g OX for oxidizer.
Source Firkin
Zero CC tileable wood texture, made by me procedurally in Neo Texture Edit.
Source Sojan Janso
Black brick wall pattern. Brick your site up!
Source Alex Parker
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.
Source Firkin
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
The image is a remix of "edo pattern-samekomon".I changed the color of dots from black to white and added BG in light-yellow.
Source Yamachem
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Farmer could be some sort of fabric pattern, with a hint of green.
Source Fabian Schultz
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
A lot of people like the icon patterns, so here’s one for your restaurant blog.
Source Andrijana Jarnjak
Prismatic Abstract Line Art Pattern Background
Source GDJ