Embossed lines and squares with subtle highlights.
Source Alex Parker
Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape 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
The classic notebook paper with horizontal stripes.
Source Are Sundnes
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Prismatic Basic Pattern 2 No Background
Source GDJ
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
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This metal background pattern resembles a metal plate with rivets. Solid rivets on a metal plate.
Source V. Hartikainen
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Tiny circle waves, almost like the ocean.
Source Sagive
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin