From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
Prismatic Abstract Geometric Background 4
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
Lovely pattern with splattered vintage speckles.
Source David Pomfret
From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.
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
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
This yellow background consists of a pattern of glossy gold buttons arranged in polka dot style on a seamless texture. Here's a pale yellow background pattern. Feel free to use it for your needs!
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.
Source V. Hartikainen