Here's a bluish gray striped background pattern for use on web sites.
Source V. Hartikainen
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
A version without colours blended together to give a different look.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.
Source Firkin
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861
Source Firkin
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
A free pink background pattern.
Source V. Hartikainen
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Handbook of the excursions proposed to be made by the Lincoln Diocesan Architectural Society, on the 27th and 28th of May, 1857', Edward Trollope, 1857.
Source Firkin