I used to sing Portia a lullaby every night before bed. It was part of her bed-time routine while she was still in a crib. When she graduated to a big girl bed, she didn't seem to want her lullaby anymore. It wasn't until very recently that she started asking for one again. Now she's much too big to rock, so I lay next to her on her bed and sing it into her ear. I think it's her way of putting off bedtime for just a little bit longer, but I'm glad she needs me again. I have a couple of songs I rotate--Lullaby and Goodnight by Brahms and Dream a Little Dream by the Mamas and the Papas, which she calls "Stars Shining".
Portia discovered Jillyboo (our cat) asleep and thought she needed a lullaby. I particularly love the way she does "her opera" while she sings.