A seamless background pattern with impressed gray dots.
Source V. Hartikainen
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
Alternative colour scheme to the original.
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
ZeroCC tileable beechwood wood texture, generated in Neo Texture Edit by me. CC0
Source Sojan Janso
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
A new take on the black linen pattern. Softer this time.
Source Atle Mo