Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Prismatic Hexagonalist Pattern No Background
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
A heavy hitter at 400x400px, but lovely still.
Source Breezi
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
Inspired by an image that was uploaded to Pixabay by geralt
Source Firkin