The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using 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
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
A green background pattern with warped vertical stripes and a grunge look.
Source V. Hartikainen
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The image depicts a seamless pattern of Japanese Edo pattern called "kikkou-matsu" or "亀甲松" meaning " tortoiseshell-pinetree".The real pinetree is like this: https://jp.pinterest.com/pin/500744052301065077/
Source Yamachem
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
A classic dark tile for a bit of vintage darkness.
Source Listvetra
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ