At the opening keynote of the New England Independent Booksellers Association's Spring Forum this week in Manchester, N.H., Betsy Groban (l.), whose first children's book, published last week, is Pizza for Pia (Simon Spotlight), interviewed Lois Lowry, author of The Giver, whose latest book is Tree. Table. Book. (Clarion Books). The two friends shared many amusing stories about Lowry's life and career with a hall full of New England booksellers.