I am making an assumption that this marriage of William Hopkins & Mary Tibbetts, of John, belongs to this Mary, because the dates fit her age and locality.
[S012741] Gordon L. Remington, Sabin-Remington-Hunt Notes, in "The New England Historical and Genealogical Register", (Vol. CXLVII, October 1993, No. 588), 374 & 375.
[S012511] James N. Arnold's Vital Record of RI, East Greenwich -- Births & Deaths.
[S012741] Gordon L. Remington, Sabin-Remington-Hunt Notes, in "The New England Historical and Genealogical Register", (Vol. CXLVII, October 1993, No. 588), 374.
[S012498] James N. Arnold's Vital Record of RI, East Greenwich -- Marriages, 79.