There were multiple attempts made to secure a commemorative 50-cent piece for the 1930 Massachusetts Bay Colony (MBC) Tercentenary, but each failed to gain approval. (You can read more here:
What If? 1930 Massachusetts Bay Colony Tercentenary.)
Dozens of privately-struck medals were produced for the Tercentenary, however. Here's my favorite of the bunch:
1930 Massachusetts Bay Colony Medal by Laura Gardin Fraser

I've posted about a few MBC Tercentenary medals, you can check them out here:
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1930 Massachusetts Bay Colony 300th Anniversary - #1 / Laura Gardin Fraser-
1930 Massachusetts Bay Colony 300th Anniversary - #2 / City and Town Committees-
1930 Massachusetts Bay Colony 300th Anniversary - #3 / Coin Sponsor IssueThere were a few successful US commemorative coin proposals that did result in issued half dollars that have a direct connection to the Massachusetts Bay Colony.
First is the 1935 Connecticut Tercentenary Half Dollar. The Colony was founded by Thomas Hooker, a preacher, who left the Massachusetts Bay Colony in 1636 to establish Hartford and the Connecticut Colony. Hooker left Massachusetts due to disagreements with the Colony's leadership over voting rights and land use.
1935 Connecticut Tercentenary

The next connection of the dots is the 1936 Providence Plantations and Rhode Island Tercentenary Half Dollar. Williams left Massachusetts to form the Providence Plantations / Rhode Island Colony to promote religious freedom for all - something not available in the MBC.
1936 Providence, Rhode Island Half Dollar
A third connection to the Massachusetts Bay Colony is found in the 1936 York County, Maine Tercentenary Half Dollar. Maine, including the present-day York County, was once part of Massachusetts (from 1647 through Statehood in 1820).
1936 York County, Maine Tercentenary Half Dollar

So, if you're a Massachusetts Bay Colony fan, you needn't fret about the lack of an associated US commemorative coin - connection options abound!
For other of my posts about commemorative coins and medals, including other stories about each of the half dollars presented here, see:
Commems Collection.