From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Zero CC tileable grass texture, photographed and made by me. CC0
Source Sojan Janso
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
From a drawing in 'Cassell's Library of English Literature', Henry Morley, 1883.
Source Firkin
A new take on the black linen pattern. Softer this time.
Source Atle Mo
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Remixed from a JPG that was uploaded to Pixabay by Osckar
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry
This is a seamless pattern of a woody texture.The original image is here:https://pixabay.com/ja/users/ClassicallyPrinted-1302233/
Source Yamachem
Abstract Tiled Background Extended 11
Source GDJ
Same as the black version, but now in shades of gray. Very subtle and fine grained.
Source Atle Mo
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
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
A background pattern with blue on white vertical stripes.
Source V. Hartikainen
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
Same classic 45-degree pattern, dark version.
Source Luke McDonald
From a drawing in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
U.S.-based National Fire Protection Association standard fire diamond for flagging risks posed by hazardous materials. The red diamond has a number 0-4 depending on flammability. The blue diamond has a number 0-4 depending on health hazard. The yellow has a number 0-4 depending on reactivity. the white square has a special notice, e.g OX for oxidizer.
Source Firkin