Function. Plants also have a pH rating. Plants whose pH matches the soil's pH can take up nutrients more efficiently than plants with a pH rating different than the soil. Pine trees and the needles that they produce prefer acidic soil.
Price of a Stamp. The current price of a first class stamp is 49 cents. A domestic first class letter (1 oz.) is 49 cents. The price of each additional ounce is 21 cents. It will cost you 34 cents to send a domestic postcard.
It is currently worth $.47 US. Forever stamps are designed to be the equivalent of whatever the current price of a first class stamp is, no matter when the stamp was purchased. In other words, if you bought a forever stamp in 1983 for $.25, it is worth $.47 today.