Most people have few if any items that once belonged to a grandparent or great-grandparent.
Rarely is a descendant lucky enough to have inherited a locket or comb or watch or Bible or lock of hair, let alone any old letters, diaries, or photographs. Almost all of it probably was thrown away because it became broken, unusable or, most of all, unwanted or unappreciated. Generally, those bits of material with family heritage value that do manage to survive are not saved in proper ways, so they deteriorate or become damaged or ruined. The bottom line is your family records must be valued or they risk being thrown away. They must be protected to prevent damage, ruined or lost.