Here, off the top of my head, are some of the best postpartum gifts I've ever received:
A week of meals (Thank you wonderful people!!)
A batch of muffins
A busket of granola
Pillars of the Earth
A pint of Kopp's red raspberry custard (which, sadly, I can't hope to receive again in my current locale)
Observation 1: These are almost all food. The joy of the meals is self-explanatory, but why should I still remember so fondly a dozen muffins I received over 8 years ago? Because they were the only thing I ate for as long as they lasted. For some reason, when I have a new baby, I cannot feed myself. I stand in the kitchen, feeling hungry, holding the baby, looking at all the food there, and thinking: It's all too hard. I can't do it. And I wander back out, sad and still hungry. This has improved since my mother-in-law has made a habit of coming to stay with us for a while when we have a new baby. I awaken from a nap with the baby on one side of me and a plate full of tacos lovingly tucked in on the other. But the problem can persist for a long time, so if you want to help a postpartum lady out, unwrap a bunch of string cheeses and put them front and center in her fridge with a note that only she's allowed to eat them.
Observation 2: Pillars of the Earth caught me by surprise, but wow. I read that book day and night for a week, and although real me felt like pure junk, imaginary me was having the time of her life building cathedrals (disclaimer: there was quite a bit of yucky stuff I skipped, particularly with the skittery postpartum brain). Now I always save a giant book I really want to read for postpartum. It helps.
Observation 3: You can never have too many sweat pants, especially postpartum.