What secret were Miguel and Alfonso hiding from Esperanza and Mama?

Alfonso and Miguel fashioned a shrine to Our Lady of Guadalupe with a small garden of roses around it - Papa's roses to surprise Mama and Esperanza. Miguel confesses that he and Alfonso saved some of the roses after the fire and carried them to California in an oilcloth. When she sees roses from both hers and Miguel’s old rose bushes, Esperanza is moved.