Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Same as gray sand but lighter. A sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Abstract Tiled Background Extended 10
Source GDJ
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel
Prismatic Floral Background No Black
Source GDJ
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
To get the repeating unit, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Remixed from an image that was uploaded to Pixabay by CatherineClennan
Source Firkin
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin