Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
From a design in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Lovely pattern with splattered vintage speckles.
Source David Pomfret
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Nicely executed tiling for an interesting pattern.
Source Ignasi Àvila Padró
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
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
Prismatic Geometric Tessellation Pattern No Background
Source GDJ