Cut bread into rounds that fit snugly inside 4-oz ramekins. To "stale", put rounds in a single layer in a 200-degree oven for an hour. Turn halfway through.
In medium, non-reactive saucepan, heat berries and sugar over medium heat, stirring occasionally, until berries release their juice and the sugar is dissolved, about 5 minutes. Remove from heat. While cooling, stir in lemon juice.
Spray ramekins with cooking spray and place on rimmed cookie sheet. With slotted spoon, put about 1/4 cup of berries in bottom of each ramekin. Then lightly soak rounds of bread in the berry juice and place on top of fruit. Repeat both steps, for two layers of fruit and two layers of bread. The bread should sit above the ramekin lip.
Top with remaining juices and cover ramekins loosely with plastic wrap. Place a second cookie sheet on top and weight with several heavy cans.
Refrigerate puddings for at least 8 hours or up to 24 hours. To release puddings, run a paring knife around ramekins. Invert, unmold and serve. Top with whipped cream.