How to make an interesting folk ritual? As a game master, you can always lead by example - i.e. prepare a brief, yet thoughtful and engaging ritual on a paper and then act it out in front of the players. A short poem, a haiku, a sand drawing, etc., etc. - whatever you fancy, whatever matches the in-game culture.
A short in-game quest may involve the players trying to impress someone of a foreign culture (a foreign culture with all the rituals and customs). In order for the players to score some "bonus points" with the foreigner, you may suggest the players to learn the foreigner's customs and impress their target with their newly acquired cultural knowledge once the time is right (invite the foreigner for a diner, etc.)
As for the folk rituals, they always reflect something. Let's explore the food rituals a bit as an example, and draw some theory along the way ...
Nowadays, the modern person goes to a diner, or just buys a snack whenever feeling hungry. In the old days, fetching food wasn't all that easy, reliable and it did require some effort. A hunter might have searched the woods for a few hours before successfully hunting down a rabbit; similarly, a farmer must have spent most of the day on the field before returning home for the spoils of his efforts, etc.
In this regard, food on the table represented fruits of our labors, something to look forwards to - a success. In this interpretation, the ritual right before eating stood for closure on success.
Another perspective on eating: all the members of the family gather up in from of the table; and in such an occasion, they remind themselves of their virtues ("poems" like The Lord's Prayer can serve this function).
The people participating in a series of activities leading to a ritual, unless ignorant to the ritual itself, go through a specific cognitive experience. If you want your players to really immerse themselves in a ritual, I'd suggest making them experience the same process (for a diner ritual, let's make them work for their real-world food, an during that nasty little experiment, let's also starve them a bit to boot).