Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
Zero CC tileable yellow craft paper; scanned and made by me. CC0
Source Sojan Janso
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Same classic 45-degree pattern, dark version.
Source Luke McDonald
White circles connecting on a light gray background.
Source Mark Collins
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
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
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin