What does this very strange dream mean?

Well. ive had this dream several times about this women. Sometimes she looks old, and sometimes young. But she always has white hair. she is always picking flowers right outside my bedroom window. I see her in my dream a lot but most of the time i ignore her. Then in one dream i see her out side my window and i actally tap on the window at her. I feel my self put on a expression of pure fear. Then, she looks up. I dont know what her face looks like. I just know that she at first look at me with equal fear, then suddenly smiles and laughs. I wake up....what does it mean? Ive dreamed of her for years... Every time I see something elso of her like a small part of her hand. or part of her brown skirt. The smile she gave me gave me chills for weeks. I dont like looking at mirrors becuase when i looked at my eyes once through the mirror, i could have sworn i saw her, smiling. I dont know anyone that has died. But when i was little i went to a cemetary and saw a grave with the same name as mine except for one letter. The dream scares me. please help.