This is a simple flap book from Usborne that does a pretty good job introducing feelings to young children and helping initiate discussion. I could nitpick (always, ha), such as pointing out that defining feelings as what we feel isn't that helpful (it says more, but that's how it begins the definition), but I still appreciate it overall, and the kids (ages 3, 6, 9, and even the 11 year-old) seem to as well.
It doesn't offer any faith perspective, which I believe is important to this topic (all topics, really...), but I can give that as I read with them, and some simple concepts fit in easily. For example, there is a flap that mentions talking to someone else about your feelings can help, and it's easy to mention that praying to God about your feelings is also helpful.
This is currently one of Hope's favorite books, and the other younger ones are interested in it too. I think it's well-timed. Hope may or may not like it just because of a picture of a snake and some other pictures she finds amusing, and because she likes to lift the flaps. ;)