Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
Prismatic Polka Dots Mark II No Background
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
The image depicts a seamless pattern of a snow crystal.I referred to a book called ”sekka-zusetsu” or "雪華図説" which means an illustrated explanation about snow crystals.This book was published in 1832 (天保3年) or Edo period.For more about "雪華図説",see here:dl.ndl.go.jp/info:ndljp/pid/2536975
Source Yamachem
This background texture resembles stone. It may be used as a background on web pages or on some of their html elements (header, borders, menu bar, etc.). Just modify it for your needs.
Source V. Hartikainen
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ
Black & white version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
From a drawing in 'Prose and Verse ', William Linton, 1836.
Source Firkin
Prismatic Abstract Background Design No Black
Source GDJ
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Black And White Floral Pattern Background Inverse
Source GDJ
Prismatic Geometric Pattern Background No Black
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.