This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Black And White Floral Pattern Background from PDP.
Source GDJ
It’s an egg, in the form of a pattern. This really is 2012.
Source Paul Phönixweiß
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
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
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
Prismatic Polyskelion Pattern No Background
Source GDJ
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
This one is amazing, truly original. Go use it!
Source Viahorizon
Retro Circles Background 7 No Black
Source GDJ
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.
Source Firkin
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
Colorful Floral Background 3 No Black
Source GDJ
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Prismatic Hypnotic Pattern No Background
Source GDJ
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee