GF has asked for a poetry book for her birthday. Any recommended books or authors?

Pretty much what the title says. My girlfriend sometimes reads poems before bed. I don't know a whole lot beyond the occasional haiku, so I am at a loss. I thought about just googling, but I wanted to see if anyone had any recommendations that really touched you in some way. Maybe in the spirit of happiness/life/love, something positive. Any help would be appreciated! Thanks :)

Edit: A lot more replies than I thought I would get! Going to probably go to the store tomorrow and look at a bunch. Right now I'm leaning towards Mary Oliver and a few others! Big thank you to all of you for your suggestions! I am extremely excited to surprise her with quite the selection