A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The original enhanced with one of Inkscapes's filters.
Source Firkin
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
emixed from a JPG that was uploaded to Pixabay by Kyotime
Source Firkin
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
From a drawing in 'Cassell's Library of English Literature', Henry Morley, 1883.
Source Firkin
I have no idea how to describe this one, but it’s light and delicate.
Source JBasoo
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo