No, they did not exist then. Great Britain introduced the first postage stamps in 1840.
The third country to issue postage stamps was Switzerland, which introduced its own stamps in 1843. This followed the issuance of the world's first postage stamp, the Penny Black, by the United Kingdom in 1840, and the second by the United States in 1842. Switzerland's stamps featured a design known as the "Ray of Light" and were used to facilitate mail delivery within the country.
Great Britan in 1840
The first postage stamp was issued by Great Britain on 1 May 1840.
There were no stamps in 1815. The first postage stamp was introduced in 1840.
The first talking film was 'The Jazz Singer' which was introduced on October 6, 1927 in New York City.
Great Britain issues stamps without a country name. Being the first country to issue stamps, it didn't need one. Since then, all of their stamps have shown a picture of the ruling monarch on them.
Without knowing what stamps you are refering to, it is impossible to offer a value. Stamps are issued from virtually every country in the world, as well each country issues many different stamps each year.
USA
If you are talking about USA stamps then it probably is a "forever" stamp good for the first class rate of one ounce or less. It is the Liberty Bell. During the last 2 decades, the US Postal Service has issued non-denominated stamps for use when they were unsure of the amount that would be authorized for a rate increase. There is a page on their web site that shows the pictures and values for these stamps. Some stamps may not be postage stamps at all but they have the same shapes. They are advertising or hobby items. I have seen stamps with each country's flag on them for collecting.
The 32 cent First Class postage rate was introduced on 1 January 1995.
The United Kingdom was the first country to issue postage stamps. Since no other country issued stamps at the time, there was no need for the UK to name itself. The UK continues to issue stamps without a country name.But every stamp of Great Britain includes at least a profile of the current ruler, currently Queen Elizabeth II.