"since peak bone mass occurs around age 30, what should be consumed regularly prior to that time to maximize bone mass? "

Foods with calcium

The amount of bone tissue in the skeleton or bone mass can keep growing until the age of  30. It is recommended to eat food with calcium prior to this age for maximum strength and density of the bones. Examples of food rich in calcium are dairy foods, green leafy vegetables, beans, nuts, fish and a lot more.

the answer is trees if i'm not mistaken