There are many carbon patterns, but this one is tiny.
Source Designova
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
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 'A Rolling Stone. A tale of wrongs and revenge', John Hartley, 1878.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
A repeating background of beige paper with vintage look. Repeats to infinity, as usual.
Source V. Hartikainen
A seamless background texture of old cardboard.
Source V. Hartikainen
From a drawing in 'A Guide to the Guildhall of the City of London', John Baddeley, 1898.
Source Firkin
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
I scanned a paper coffee cup. You know, in case you need it.
Source Atle Mo
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat