Here's a bluish gray striped background pattern for use on web sites.
Source V. Hartikainen
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin
A brown seamless wood texture in a form of stripe pattern. The result has turned out pretty well, in my opinion.
Source V. Hartikainen
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Tweed is back in style – you heard it here first. Also, the @2X version here is great!
Source Simon Leo
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Hundert Jahre in Wort und Bild', S. Stefan, 1899.
Source Firkin
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
You know you love wood patterns, so here’s one more.
Source Richard Tabor
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
Uses spirals from Pixabay. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin