This is so subtle you need to bring your magnifier!
Source Carlos Valdez
By popular request, an outline version of the pentagon pattern.
Source Atle Mo
Fix side and a seamless pattern formed from circles.
Source SliverKnight
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
It looks very nice I think.
Source V. Hartikainen
A version without colours blended together to give a different look.
Source Firkin
The image is a seamless pattern which is derived from a vine .Consequently, the vine got like dots via vectorization.The original vine is here:jp.pinterest.com/pin/500744052301410188/
Source Yamachem
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
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Prismatic Abstract Geometric Background 3
Source GDJ