A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
Zero CC tileable yellow craft paper; scanned and made by me. CC0
Source Sojan Janso
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
A pale olive green background with a seamless texture.
Source V. Hartikainen