My grandma gave me a bracelet a year before she passed away, and that's my most valuable possession. I don't wear it anymore, but I do have one of my plushies wearing it (which I keep at the top of my bookshelf). Every time I look at this bracelet, it reminds me of all the time that I've spent with her as a kid. She used to bake me cookies, put me to bed, take me out on the park, play hide and seek with me, and more. I loved her a lot, sometimes more than my own parents.
My second most important thing has gotta be my laptop. Most of the time, it's the only thing that keeps me entertained. If I ever lose it (which I hopefully won't), then I'm not sure if I'll even be able to live. xD