A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
Derived from a drawing in 'Historiske Afhandlinger', Adolf Jorgensen, 1898.
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Number 1 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Background formed from the original with an emboss effect
Source GDJ
The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:https://jp.pinterest.com/pin/500744052301423641/
Source Yamachem
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
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
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
This metal background pattern resembles a metal plate with rivets. Solid rivets on a metal plate.
Source V. Hartikainen
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin