Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Heavily remixed from a drawing in 'Barbara Leybourne; a story of eighty years ago', Sarah Hamer, 1889.
Source Firkin
Prismatic Polka Dots Mark II 2 No Background
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
Non-seamless pattern drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
An aged paper background tile with smeared and pressed text.
Source V. Hartikainen
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The image depicts a seamless pattern made using a bird's face.
Source Yamachem