This is so subtle you need to bring your magnifier!
Source Carlos Valdez
The classic notebook paper with horizontal stripes.
Source Are Sundnes
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The image depicts meshed silhouettes of various things.The original image is an OCAL clipart called "Enter FOSSASIA 2016 #IoT T-shirt Design Contest" uploaded by "openclipart".Thanks.
Source Yamachem
A seamless texture of worn out "cardboard".
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
Prismatic Floral Background No Black
Source GDJ
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen