People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Derived from an image that was uploaded to Pixabay by TheDigitalArtist
Source Firkin
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Looks like an old rug or a computer chip.
Source Patutin Sergey
From a drawing in 'Less Black than we're painted', James Payn, 1884.
Source Firkin
Sort of like the back of a wooden board. Light, subtle, and stylish, just the way we like it!
Source Nikolalek
Tile-able Dark Brown Wood Background. Feel free to use it as a background image in your designs or somewhere on the web. By the way, the color seems to be close to Coffee Brown.
Source V. Hartikainen
Zero CC tileable bark texture, photographed and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo