A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The image depicts a seamless pattern which includes hexagonally-aligned gourds with BG in light-brown.
Source Yamachem
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
The starting point for this was a texture drawn with the 'Radial Colors' plug-in in Paint.net.
Source Firkin
A tile-able background for websites with paper-like texture and a grid pattern layered on top of it.
Source V. Hartikainen
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
A version without colours blended together to give a different look.
Source Firkin
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
Zero CC bark from fur tree tileable texture, photographed and made by me. CC0
Source Sojan Janso
A bit strange this one, but nice at the same time.
Source Diogo Silva
Greyscale version of a pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Colour version of the original seamless pattern.
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin