I think, this is Daphne striata, Steinröschen (a Seidelbast species) in german. They smell very strong and pleasant and blossom on limesone soils mainly in june/july. I like their smell but they are VERY poisonous.
Oh, I didn't know that, Michael! Very poisonous! And the name - I don't remember where I got the name 'Thlaspi rotundifolium'. I will change the title to 'Daphne striata'.