Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
The original has been presented as black on transparent and stored in the pattern definitions. To retrieve the unit tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
The classic notebook paper with horizontal stripes.
Source Are Sundnes
Prismatic Hexagonalist Pattern No Background
Source GDJ
A tile-able background for websites with paper-like texture and a grid pattern layered on top of it.
Source V. Hartikainen
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Sounds like something from World of Warcraft. Has to be good.
Source Tony Kinard
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
Same as the black version, but now in shades of gray. Very subtle and fine grained.
Source Atle Mo
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
A version without colours blended together to give a different look.
Source Firkin
There are many carbon patterns, but this one is tiny.
Source Designova
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin