Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
A seamless pattern of "sewn stripes" colored in light gray.
Source V. Hartikainen
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Remixed from a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Remixed from a PNG that was uploaded to Pixabay by k_jprather
Source Firkin
Abstract Ellipses Background Grayscale
Source GDJ
Seamless Light Background Texture.
Source V. Hartikainen
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo