Number five from the same submitter, makes my job easy.
Source Dima Shiper
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
A version without colours blended together to give a different look.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
Sharp but soft triangles in light shades of gray.
Source Pixeden
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
An aged paper background tile with smeared and pressed text.
Source V. Hartikainen
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Prismatic Groovy Concentric Background 4
Source GDJ
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
I’m starting to think I have a concrete wall fetish.
Source Atle Mo
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Run a restaurant blog? Here you go. Done.
Source Andrijana Jarnjak
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
Seamless pattern formed from a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
A background pattern with blue on white vertical stripes.
Source V. Hartikainen
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen