Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
Prismatic Curved Diamond Pattern No Background
Source GDJ
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
A very slick dark rubber grip pattern, sort of like the grip on a camera.
Source Sinisha
From a drawing in 'A Life Interest', Mrs Alexander, 1888.
Source Firkin
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
From a drawing in 'From Snowdon to the Sea. Striking stories of North and South Wales', Marie Trevelyan, 1895.
Source Firkin
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
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
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
A chequerboard pattern with a fruit theme. The fruits are from a posting by inkscapeforum.it.
Source Firkin
Black And White Floral Pattern Background Inverse
Source GDJ
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Prismatic Abstract Line Art Pattern Background
Source GDJ
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
This background image is great for using in web design or graphic design projects. And don't forget to visit the homepage. I frequently update this resource with fresh tileable backgrounds.
Source V. Hartikainen