Square low walnut table  

walnut table
hi Heidi,
something like this ?
ite
http://www.0900-design.nl/catalog/product_info.php?products_id=628

yes...
your local timberyard.

I wish I could be more specif...
I wish I could be more specific, but look for mid-century Drexel coffee tables. Drexel produced one that was a nice walnut rectangular block with two(?) drawers. It does have legs, but they're small and the table sits quite low to the ground. It's a beautiful table.

Dera Heidi
There is nothing rectangular on this table, but just over a week ago i discovered it in an exhibition on Flemish design here in Montreal's Design Center. It was the wallnut version of Casimir's "Schaal nr 1" and it is just perfect...if you like wood, that is. Cutting through the wood the way this round shape does, with end wood on both sides slowly changing into the quite dramatic colours of length-wood walnut...leaves you speechless. Walnut is not my favorite wood, but in this shape it is spectacular....and it has no legs!
You have to flip through the pages of the website to page 14 by clicking on the pagenumbers...pleasant but slow.
http://www.casimir.be/casimir_v3.html

Rectangular tables
see this
http://www.cor.de/_products/3_tableschairs/e_conseta.php

I agree with Vivienne.........
If what you really want is an unadorned block of walnut, then I'd find the best timber merchant you can..and buy just that !