Since I am working on Memory Quilts, I can help.
Usually, as I understand it, they are made from favorite clothing of the one who has passed on. The block/quilt design is up to you or whoever has asked you to make it. The type of clothing can sometimes point you in the direction of block choice. i.e. Hawaiian shirts might lead you to make a Hawaiian quilt from them, or a novelty quilt where you make them into tiny Hawaiian shirts set in square blocks.
I have seen some gorgeous ones done with the New York Beauty block. They were all Tommy Bahama type shirts, so the quilt maker was able to use some very bold and fun colors with them.
I have done 3 so far, and one more in the works, all different designs. I posted them in pics.
Hope this helps!
Wendy