Not too familar of the RI area but lots in my town and Middleboro. Assawopsett was the place where King Phillips war started pretty much. Middleboro used to have a great museum of Indian artifacts from the Pond area. Not sure where that is housed anymore. A couple Wompanoag burial grounds too in my area. Pretty much kind of the middle of the trek from Plymouth to Mt. Hope. Plymouth is worth a father son trip too. Probably soon we will have an Indian casino too.
http://en.wikipedia.org/wiki/Assawompset_Pond