Geometric triangles seem to be quite hot these days.
Source Pixeden
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
Zero CC tileable cork floor, photographed and made by me. CC0
Source Sojan Janso
Prismatic Chevrons Pattern 5 With Background
Source GDJ
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
The name tells you it has curves. Oh yes, it does!
Source Peter Chon