Daphne laureola? I can't say for sure but it doesn't look quite like DL. They are growing in my garden by the dozens thanks to a neighbour who thinks they're beautiful - I'll go out tomorrow and compare your photo to the reprobates I see every day.
Wow I hope you're right! I did not see any large plants so it would make sense that it is perennial. I've never seen these growing in the wild. I am anxious to go back in July to see if they are in bloom.
Please don't tell me this is what I think it is... I'm assuming you were afraid that the plant you found was Daphne laureola and the similarities are notable at first glance. Wouldn't it be wonderful if we could wave a magic wand and turn every DL into Lilium columbianum?