A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Remix from a drawing in 'Ostatnie chwile powstania styczniowego', Zygmunt Sulima, 1887.
Source Firkin
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
The image is a remix of "edo pattern-samekomon".I changed the color of dots from black to white and added BG in light-brown.
Source Yamachem
Here's an yet another background for websites, with a seamless texture of wood planks this time.
Source V. Hartikainen
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
This is the remix of "plant pattern 02".I changed the object color to white and the BG to purple.The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:jp.pinterest.com/pin/500744052301423641/
Source Yamachem
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ