“ A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for 'study' by the Guild. The party's presence will be 'requested' for this expedition.”
“ The religion believes in reincarnation, but that you will be reborn in the past. People of today are those re-born of tomorrow, with some discarded as trash. The most pure will be eventually reborn in the mythical paradise-like past, where people lived for hundreds, or maybe even thousands of years.
This goes nicely with beliefs into foresight (you know a little about the future because you have been there), but also to many complaints of how things are going always from bad to worse.”
“ In the far reaches of a long-lost wilderness, there stands a forgotten town inhabited only by children. Though they appear normal enough, their eyes burn with madness, and they speak in a foreign, archaic tongue. Nearly a millenia ago, a powerful spell had gone awry, or maybe it had succeeded - in any case, it ended up blessing, or cursing, an entire generation of children with agelessness. However, as the centuries passed, the children's parents grew old and died, the buildings of the town crumbled to earth, and even the civilization itself faded into history, becoming lost to time. All that remained were the children, driven mad by the psychological toll of living for hundreds of years beyond their age. In time, most children died, killed off by fighting amongst themselves, while many others were driven to suicide. Only a small handful remain, and they are a strange people indeed.”