Is it possible to collect a graveyard dirt from the dead person who cremated?

I want to do a graveyard dirt spell,,my husband died two years ago but his body was cremated.....I go to cemetery almost everyday but I am afraid to get some graveyard dirt from other grave...Is it posible to get a graveyard from a cremated dead person? if i get from my husband neighbourhood grave ..should i dig it deep? is it not possible to get it just from the surface? Anyone can help me for this problem..I really need the answer..Please give me some idea or some information about this..thanks a lot