As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Prismatic Groovy Concentric Background 3
Source GDJ
Prismatic Abstract Geometric Background 3
Source GDJ
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
To get the tile this is made up from 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
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim