In a traditional Buddhist fashion, in the early morning monks will go on the street to pass peoples house so people can give them alm (food & drink). In Thai called Tak Bat. This is practiced all over Thailand but in small town Nan with the many temples it is a wonderful sight in the early morning to see many monks on the street for receiving alms. Giving alms is a way of making merit.
WarningGiving alms is a wonderful thing to see and if with a sincere feeling also a wonderful experience to do yourself. Remember it is a religious ceremony, not a tourist show made for you! So there are a few things to consider :
If you are just going to have a look, please stay at a distance and be respectful to the people giving and to the monks. Do not walk in between the monks or the people giving alms. Do not touch the monks. Be dressed appropriately, like going to a temple.
And if you want to participate in it then ask your host (hotel) how to do. Best would be to make the food yourself so it is fresh and healthy food.