Garden Seeds Plants Herbs

http://b-and-t-world-seeds.com/sublists.htm

The world biggest seed collection, with many rare plant varieties

Amazing the number and variety of plants they have.

http://realseeds.co.uk/cucumbers.html

Nice UK company selling non-hybrid varieties and many rare vegetables.

They sell interesting things like the strawberry spinach

This company too (and organic, but it's US)

http://www.wildgardenseed.com/index.php?cPath=56&osCsid=t7actdqk6a5f9tvk7rbdjbjg10

More UK companies, they all have crazy varieties, organic and non-hybrid

http://www.tamarorganics.co.uk/pages/catalogue.php

http://www.organiccatalog.com/catalog/

http://www.vegetableseedstore.co.uk/

More focused on herbs: http://www.jekkasherbfarm.com/plants.asp

Wild flowers: http://www.meadowmania.co.uk

All kinds of flowers: http://www.suttons.co.uk/Shop/Flower+Seeds/List/