Might not be super subtle, but quite original in its form.
Source Alex Smith
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Looks like an old wall. I guess that’s it then?
Source Viahorizon
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
Original minus the background
Source Firkin
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Plywood Web Background background image for use in web design.
Source V. Hartikainen
A background tile for web with abstract repeating texture of dark "stone wall".
Source V. Hartikainen
Inspired by a design found in 'Konstantinápolyi emlékeim', Miklos Chriszto, 1893.
Source Firkin
Same as the black version, but now in shades of gray. Very subtle and fine grained.
Source Atle Mo
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A background pattern with green vertical stripes. A new striped background pattern. This time a green one.
Source V. Hartikainen
Remixed from a drawing that was uploaded to Pixabay by DavidZydd
Source Firkin
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
No, not the band but the pattern. Simple squares in gray tones, of course.
Source Atle Mo
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Prismatic Floral Background No Black
Source GDJ
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian