The Grandmother (1970)
An imaginative lad of about ten has a couple of problems: he wets his bed, and his parents are abusive and disgusting. In a spare room, he finds a bag of seeds, which he plants in soil that he's placed in the middle of a single bed. The seed sprouts and grows into a grandmother, who's loving and approving. Life with his parents and with his imagination continues. Is a smiling grandmother enough to get him through?