A mophead (hydrangea macrophylla). Lowes has many Merrit Supremes for sale here so maybe yours is one of those too.

It is presenting with doubled flowers, so that reduces the possibililties :-) I'd start with something like Double Delights Perfection just because that is a newer and more popular reblooming form but it could be a number of other similar selections........or entirely possible as a NOID as well.

I wouldn't suggest being restricted or even heavily influnced by flower color when it comes to narrowing things down - that is one of the easier things to alter or manipulate with container grown hydrangeas.