Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This metal background pattern resembles a metal plate with rivets. Solid rivets on a metal plate.
Source V. Hartikainen
Nicely executed tiling for an interesting pattern.
Source Ignasi Àvila Padró
A seamless pattern based on a tile that can be achieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamless canvas texture for using as background on websites. Colored in pale tones of brown.
Source V. Hartikainen
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
From drawing in 'Musings in Maoriland', Thomas Bracken, 1890.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay