Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
There are many carbon patterns, but this one is tiny.
Source Designova
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Remixed from an image on Pixabay uploaded by Prawny
Source Firkin
Number 1 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
This could be a hippy vintage wallpaper.
Source Tileable Patterns
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
The image depicts an edo-era pattern called "same-komon" or "鮫小紋"which looks like a shark skin.The "same" in Japanese means shark in English.
Source Yamachem
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Green Web Background, Seamless tile.
Source V. Hartikainen
He influenced us all. “Don’t be sad because it’s over. Smile because it happened.”
Source Atle Mo
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
A seamless pale yellow paper background with a pattern of animal tracks.
Source V. Hartikainen
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Vector version of a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin