From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
Light and tiny, just the way you like it.
Source Rohit Arun Rao
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks.
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
An abstract pale yellow paper-like background with stains colored in yellow and green.
Source V. Hartikainen
Here's an yet another seamless note paper texture for use as a background on websites.
Source V. Hartikainen
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
No relation to the band, but damn it’s subtle!
Source Thomas Myrman
The tile for this is based on a repeating unit close to a design on Pixabay. It can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin