Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Prismatic Hexagonalism Pattern No Background
Source GDJ
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The starting point for this was drawn on the web site steamcoded.org/PolyskelionMaker.svg
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
Classic vertical lines, in all its subtlety.
Source Cody L
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
I’m not going to lie – if you submit something with the words Norwegian and Rose in it, it’s likely I’ll publish it.
Source Fredrik Scheide
Inspired by a pattern I saw in a 19th century book. This seamless pattern was created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Orange-red pattern for tiled backgrounds.
Source V. Hartikainen
Inspired by a drawing in 'Poems', James Smith, 1881.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin