Isn't that poem already made up? I heard in a book (Holes) and then I heard it in a movie (Holes) But I like it! Heres mine, Its already been made up, it was in a welcome home card for my mom's funeral:

When I am gone, release me. Let me go. I have so many things to see and do. You musn't tie yourself to me with tears, be happy we had so many beautiful years. I gave to you my love. You can only guess how much you gave to me in happiness. I thank you for the love you have each shown. But now it's time I traveled alone. So grieve awhile for me, if grieve you must. Then let your grief be comforted by trust. It's only for awhile that we must part, so bless the memories within your heart. I won't be far away, for life goes on. So if you need me, call and I will come. Though you can't see or touch me, I'll be near. And if you listen with your heart, you'll hear all my love around you soft and clear. And then, when you must come this way alone, I'll greet you with a smile and say "Welcome Home."

The poem is called Welcome Home. Keep in mind, I didn't make it up!
It was in a "In Loving Memory" card for my mom's funeral. Merry Christmas!