I am not very good are identifying them because they resemble each other so much. To help others do that, I suggest you post pictures that show the bush, another of the leaves and another picture of the blooms. Also, any idea how old the hydrangea might be (counting only your years of house ownership). Have you kept it at that height or it has not grown taller than that?

This is my second year in my home. I moved in during fall of 2008 but saw this hydrangea when purchasing home in late Aug. It has always been this size. I do not even know how to prune this plant. I know it is a mophead.

I don't know of any mophead that will remain that small. Even 'Pia'(aka 'Pink Elf') which is recognized as a dwarf gets about double that size. The CityLine series has been bred to stay small but they will get larger than 1.5 feet (again, about 3'x3') and will need protection in your area as they are a bit more tender than other macs.

I agree. Pia and Forever Pink stretch the definition of dwarf over here since the growing season is so long in Texas but MO may be different. Do you do any form of winter protection on this hydrangea? Has it bloomed reliably during these two years? Does it leaf out from the crown in Spring or do the stems leaf out?

The answer to this next question is probably 'no' but is it possible to contact the previous owners and find out the type of mophead? Some people also put little "signs" around their plants. These labels give the name, variety, etc of each plant. Can you look around this hydrangea to see if they left one? One that may be hidden by the mulch?