Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
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
This seamless light brown background texture resembles a wallpaper with vertical stripes. One way to use it is as a tiled background on web sites.
Source V. Hartikainen