A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
From drawing in 'Musings in Maoriland', Thomas Bracken, 1890.
Source Firkin
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
The classic notebook paper with horizontal stripes.
Source Are Sundnes
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin