From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
An aged paper background tile with smeared and pressed text.
Source V. Hartikainen
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
White circles connecting on a light gray background.
Source Mark Collins
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The starting point for this was drawn on the web site steamcoded.org/PolyskelionMaker.svg
Source Firkin
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green