The classic notebook paper with horizontal stripes.
Source Are Sundnes
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A seamless background of warped stripes on paper.
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. Version with black background.
Source Firkin
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Seamless SVG vector and JPG backgrounds with faded diagonal stripes. The colors are editable.
Source V. Hartikainen
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
A green background pattern with warped vertical stripes and a grunge look.
Source V. Hartikainen
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
Love the style on this one, very fresh. Diagonal diamond pattern. Get it?
Source INS
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
CC0 and a seamless pattern from a tile drawn in Paint.net .
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 'Less Black than we're painted', James Payn, 1884.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett