Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
Remixed from a PNG that was uploaded to Pixabay by k_jprather
Source Firkin
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Abstract Line Art Pattern Background
Source GDJ
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
CC0 and seamless wellington boot pattern.
Source SliverKnight
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 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight