Kruidnoten spotting is a tradition / sport in The Netherlands. The earliest I have spotted them is August 1, although this year I haven’t seen them yet. Marco did, though, and took a photo of them at a local Albert Heijn earlier this week:

I am sure if I went to the local Jumbo grocery store (pronounced Yumbo) I would find them as well. Although I don’t see them offered online quite yet…
Kruidnoten are a confectionery to celebrate the December 5 Sinterklaas holiday. Personally I am waiting for the gevuld speculaas, which is a cake with almond paste inside. It looks like this (laurasbakery.nl). Yum!