A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
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
One more sharp little tile for you. Subtle circles this time.
Source Blunia
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
Background Wall, Art Abstract, white Well & CC0 texture.
Source Ractapopulous
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
This pattern comes in orange, and it looks as if it is "made of glass".
Source V. Hartikainen
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
You know you love wood patterns, so here’s one more.
Source Richard Tabor
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
Luxury pattern, looking like it came right out of Paris.
Source Daniel Beaton