Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
From a drawing in 'Kingsdene', Maria Fetherstonehaugh, 1878.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using 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
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin