Hi Mike and welcome to the forum. When stamps are saved in the way you are describing - a corner with numbers - it's called a plate block. I believe plate block collecting is not as popular as it once was but there are still plenty of collectors out there. The value depend somewhat on the scarcity of the particular plate numbers, but in general I wouldn't expect most plate blocks to be worth more than the stamps themselves. In other words if the individual stamps in the block were worth a dollar each I'd expect the block to be worth four dollars. Maybe someone else will have more insight.
Paul