Tile available in Inkscape using shift-alt-i on the selected rectangle
Source Firkin
This tiled background comes in red and consists of tiles that look like gemstones. It is more for blogs or social profiles, I think.
Source V. Hartikainen
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
You may use it as is, or modify it as you like.
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
Geometric triangles seem to be quite hot these days.
Source Pixeden
Might not be super subtle, but quite original in its form.
Source Alex Smith