Hmmm, maybe not. The bloom does not seem as big as I expect from hydrangeas. Most of the time, you get a single large mophead or lacecap bloom at the end of the stem but I cannot tell from the picture if you are getting separate (is it three?) blooms or one. The flower bud, before opening, looks like broccoli. The leaves tend to be heart-shaped and are either serrated or toothed, which I am not seeing either.

Please go to the link below so you can see some leaf/bloom pictures.

Here is a link that might be useful: Hydrangea Identification

Maybe a picture of the whole plant would help?

This is a pic of the whole plant. I would think it should have serated leaves also. Leaves are somewhat heartshaped.
Any help would be appreciated. Im sure my Mom ordered it from some cheap mail order catalog..you know the ones Im talking about. Nice pictures of plants and when you order, it just a stick or two for the person to plant and hope it grows. Thanks.
I have asked my sister if the bloom has more to open, and havent heard back yet.

Yes it looks to me like a Hydrangea, but I don't know which one. Al