Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
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
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Abstract Tiled Background Extended 10
Source GDJ
Sort of reminds me of those old house wallpapers.
Source Tish
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
From a drawing in 'Prose and Verse ', William Linton, 1836.
Source Firkin
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Hypnotic Pattern No Background
Source GDJ
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Prismatic Groovy Concentric Background No Black
Source GDJ
A light gray wall or floor (you decide) of concrete.
Source Atle Mo