Dear Nathan,

What you have is a Chinese stone carving marked Daoguang and also from the period I believe. Emperor Daoguang ruled China from 1821 until 1850. Its indeed a seal for sealing a letter or document with a personal name. Text on the side is refering to a gift to a mother. So could be a son giving this to his mother ( no likely it was a daughter in those days ). It appears to be a dark type of natural hard stone. Could be many things including jade or serpentine. Those stone types were used a lot and come in many colors. You see many later copy's on the market but the really good carving, the natural wear and the patin on the item make me believe its an original old piece. Nevertheless I have to give you a conditional estimation; not knowing the type of stone makes the estimation tricky. I can say if it is a jade piece it is not the best quality. I stick with that for my estimation. If you want to know more I would suggest showing it to an expert who can take it in his hand ( a good auction house would probably a good idea ).