Inspired by the B&O Play, I had to make this pattern.
Source Atle Mo
From a drawing in 'Real Sailor-Songs', John Ashton, 1891.
Source Firkin
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
I have no idea how to describe this one, but it’s light and delicate.
Source JBasoo
An alternative colour scheme to the original seamless pattern.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
Sharp but soft triangles in light shades of gray.
Source Pixeden
The image depicts a seamless pattern of pine tree leaves.
Source Yamachem
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Prismatic Abstract Background Design
Source GDJ