Why do i have these thoughts?

hey guys, sadly 2 weeks ago i lost my grandfather , after a very long battle with als(lou gehrigs disease) ,hes the second person ive lost in my life, 18 months ago i lost my grandmother(his wife) after a battle with cancer. now i do miss them both alot, but it doesent hit me right away always that their gone and their not coming back, i mean me and my dad talk about both of them like their still around, we tell so many stories, we see he is instead of he was when refering to him too. anyway my actual qusteion is, i have 2 grandparents left(my moms parents) and i really love them. and as stupid as this may seem i think to myself i have nothing to remenber them by, when they do p away(which i hope is not for a very very long time) i had a batman doll, which my grandfather gave me when i was maybe 3, but i gave it to my little cousin as a nice gesture a few years ago and now in all fairness i kinda regret it. i mean do i have a few things to remenber my grandparents by when they do p away but still i wish i just had something really special from them.my grandfather wanted to give me a mini pocket knife which he bought way before i was born at niagra falls but i couldnt accept it, i told him it yours you keep it, its really nice but ya and again i kinda regret doing this to. and its really hard to explain some of my thoughts in writing so i am seriously sorry that alot of this doesent make sense but theirs not much i can truly explain. these thoughts were triggered in my mind tonight just by me simply looking at posters on my wall and remenbering wheir i got the posters from and why i put that particular poster on my wall. anyway what happend exactly was i was looking at a hilary duff poster which i got from a magazine and i remenber so well the day i got this magazine, and i remenber i brought exactly 7 dollars with me to the store(2 dollars for hockey cards 5 for a magazine) anyway i forgot about taxes( i was 11 at the time) and anyway my grandfather was the one who took me to the store( we just went for a walk to kill some time and we just happend to stop by the convience store) and anyway i was obviously short on cash(because i forgot about taxes as i said) and i remenber my grandfather going to me no no dont worry about it i pay for you i pay for you. and he wouldnt even let me use the money i had and pay a few dollars extra. but anyway im wondering why are these thoughts just magically popping into my head.