Reddit mentions of A Child's Book of Blessings and Prayers

It sounds like an oxymoron, but non-religious prayers (i.e. not directed at any sort of god) can totally work. For example, expressing gratitude for a meal in the context of the Earth nurturing the plants that grew your food, the people who gathered it and transported it to your store, the family members who cooked it into a delicious dinner, etc. You can leave off the "amen" (or not, since literally it just means "so be it") and it becomes a lovely secular exercise in pausing to appreciate the good things in your lives. I also play what I call "the thank-you game" with young kids, finding things to be thankful for at random times during the day (stopped at a red light? "thank you car, for getting us where we need to go!" getting wet in the rain? "thank you rain, for making the plants grow and giving us water!" sitting around at home? "thank you house, for keeping us nice and warm!" etc).

You could also explore prayers from a variety of different religions (for example, check out a book like A Child's Book of Blessings and Prayers or A Child's Book of Blessings). I think this helps emphasize that prayers are a pretty universal way that humans across the centuries have sought comfort and self-reflection, regardless of the specific religious beliefs involved. Your little one might be a bit young for it right now, but I also have to recommend the book Grandad's Prayers of the Earth as a lovely non-religious interpretation of prayer. Going back to the theme of gratitude, The Secret of Saying Thanks is another beautiful book by the same author.