The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
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
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The image is a remix of "edo pattern-samekomon".I changed the color of dots from black to white and added BG in light-yellow.
Source Yamachem
A brown seamless wood texture in a form of stripe pattern. The result has turned out pretty well, in my opinion.
Source V. Hartikainen