Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
A new take on the black linen pattern. Softer this time.
Source Atle Mo
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A lot of people like the icon patterns, so here’s one for your restaurant blog.
Source Andrijana Jarnjak
Prismatic Polka Dots Mark II No Background
Source GDJ
Psychedelic Geometric Background No Black
Source GDJ
Prismatic Abstract Geometric Background 4
Source GDJ
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
A colourful background drawn originally in paint.net and vectorised in Vector Magic.
Source Firkin
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A new take on the black linen pattern. Softer this time.
Source Atle Mo
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees