New Stamp Prices Go Into Effect Today. One Ounce First Class Now 44 Cents

From USPS site:

On May 11 the price for a 1-ounce First-Class Mail stamp will increase from 42¢ to 44¢. Prices for other mailing services — Standard Mail, Periodicals, Package Services (including Parcel Post), and Extra Services — will also change. The average increase by class of mail is at or below the rate of inflation as measured by the Consumer Price Index.

See Complete Price List (PDF)

Customers can use their Forever Stamps — regardless of when purchased — to mail 1-ounce letters after the price change, without the need for additional postage. Forever Stamps are widely available through Post Offices, commercial retail outlets such as grocery stores, and online. Prices for mailing services will continue to adjust each May. Prices for most shipping services, including Express Mail and Priority Mail, were adjusted in January and will not change in May.