Melissa Lavigne has done a lot of kayaking on the St.  John River in Fredericton. But recently, as she explored the shoreline on the city’s south side, she came across a couple of grave discoveries, one with a possible link to a passenger on the Mayflower. Lavigne found a headstone and a grave marker for two different men, buried 67 years apart in different cemeteries, kilometres away from each other. “It’s very weird,” Lavigne said. “I hope this river isn’t trying to tell me something.” WATCH | A headstone more than 100 years old pokes out of St. John River:A pair of grave discoveries made by Fredericton kayakerA kayaker out for a paddle discovered…