A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Sort of reminds me of those old house wallpapers.
Source Tish
Prismatic Abstract Geometric Background 4
Source GDJ
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
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
No, not the band but the pattern. Simple squares in gray tones, of course.
Source Atle Mo
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Formed by distorting an image on Pixabay that was uploaded by gustavorezende. To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Dark blue concrete wall with some small dust spots.
Source Atle Mo