Light gray version of the Binding pattern that looks a bit like fabric.
Source Newbury
Might not be super subtle, but quite original in its form.
Source Alex Smith
Uses spirals from Pixabay. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A free web background image with a seamless concrete-like texture and an Indian-red color.
Source V. Hartikainen
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
You may use it as is, or modify it as you like.
Source V. Hartikainen
This is sort of fresh, but still feels a bit old school.
Source Martuchox
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
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
The original enhanced with some gradients.
Source Firkin
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts