Depending on where you are in the  states there are so many options. I think if your googlinjg churches thats one problem. Not too many native indians use what we consider a church.

There are pow wows, drum circles, and each summer the big Sundancer festivals all over the western states. Some are open to the public some like the sun dancers are invite only but non natives def get invites once they prooved their intentions.

Also look up native american medicine wheel classes. Thats the bread and butter of their beleiefs and many classes and native leaders are happy to share this with non natives.