Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
It looks very nice I think.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Submitted in a cream color, but you know how I like it.
Source Devin Holmes
Prismatic Groovy Concentric Background 5
Source GDJ
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
White handmade paper pattern with small bumps.
Source Marquis
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861
Source Firkin
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
A repeating background for websites with a texture of black groove stripes.
Source V. Hartikainen
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Remixed from a drawing in 'Incidents on a Journey through Nubia to Darfoor', F. Ensor, 1891.
Source Firkin