Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
From a drawing in 'A Guide to the Guildhall of the City of London', John Baddeley, 1898.
Source Firkin
Prismatic Abstract Geometric Background derived from an image on Pixabay.
Source GDJ
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
There are many carbon patterns, but this one is tiny.
Source Designova
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen