Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
Prismatic Abstract Geometric Background 2
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Here's a quite bright pink background pattern for use on websites. It doesn't look like a real fur, but it definitely resembles one.
Source V. Hartikainen
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
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
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa