If you want png files of thisu can download them here :
Source Viscious-Speed
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Prismatic Polka Dots Mark II 2 No Background
Source GDJ
Geometric triangles seem to be quite hot these days.
Source Pixeden
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
You may use it as is, or modify it as you like.
Source V. Hartikainen
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady