Harvard has even more museums than I knew about, and you can visit for free. Be careful if you like your flesh intact though.

My family and I have recently discovered the Harvard museums. We had been to Natural History and one of the art museums, each as part of a free one-time event, but I had no idea about the museums that don't charge admission at all, or that they have free days that are more than the hour or so once a month that most of the museums offer. I also didn't know that the others existed outside of Natural History and two art museums.

So, here's my roundup of the museums:

Harvard Museum of Natural History

It mainly features taxidermied animals. It also has dinosaur and other prehistoric skeletons and models, a huge whale skeleton, blown glass models of marine life, and an interactive ecology forest geared toward toddlers and preschoolers. It's $12 for adults, $8 for kids, free under 3. So, like half as much as most of the museums in the area. Admission to this museum gets you into the Peabody Museum as well. They have two free days for Massachusetts residents, Sunday 9am-12pm and Wednesday 3pm-5pm. It's also free for K-12 teachers and active duty military families. Passes are also available at public libraries, which admit up to 4 people for $6.

They also offer classes on various topics for children and families (some are drop-off, others are not), which are all either free or reasonably priced. A child in my household attended a free class on spiders last year, which was fabulous, and was taught by female scientists, which I thought was great. 

Can we talk about this pin though? It's got teeth. Not only did it stay on my clothes without sliding around whatsoever, but it also bore down and refused to move at all. I had to pry the jaws open, several times since the first few times it snapped back shut, threatening to take my finger with it, and delicately slide my shirt out of it one tooth at a time so it didn't rip any flesh fabric. I give the museum an extremely positive rating. It's great for kids and adults alike. This pin though. 

Peabody Museum of Archaeology and Ethnology

This one has weapons from various cultures and eras, amazing ancient pottery from various regions of the world, an exhibit on ocarinas, several exhibits on Native American (north, central, and south Americas) history and culture, and a Dio de Los Muertos altar. It's pretty captivating for all ages.

Same admission rates and same free days at Natural History. They're adjoining, and getting into one via any rate gets you into both. Unsure whether this museum involves vicious maneating pins.

Collection of Historical Scientific Instruments

Just what it says. It's always free. Doesn't require any pins, demonically possessed or otherwise.

Semitic Museum

Has a model of a mud house from Ancient Israel, Ancient Egyptian funerary arts (but not actual mummies -- the MFA has some if you need to get a fix), pottery from various locations and eras in the Middle East. Nice explanations of how these cultures (and Ancient Roman and Greek cultures to an extent) intersected in ancient times. Probably not quite as interesting for preschool kids unless they're specifically interested in the topic, though the house might interest them. Always free, doesn't involve any attempts to slash flesh or rip clothing (which, while we're on the subject of ancient Israelites, tearing clothing is part of an ancient Hebrew mourning tradition called Kriah. The more you know.™)

Harvard Art Museums: Fogg, Busch-Reisinger, Sackler

Admission covers all three museums. $15 for adults, free under 18. Free for Massachusetts residents Saturdays from 10am-12pm. The museums all feature a lot of modern art, and collections that change frequently. Check the website for specific information, or just go visit. I don't recall whether these museums involve being maimed by angry bloodthirsty pins.

Warren Anatomical Museum (in the Longwood area)

Free. Has instruments, photos, human remains. Really cool. Has photos of people flaying open bodies, but no pins that do so.

Membership to the museums

$85 for a family, can be less if you have a Harvard ID (I believe you can use any type, including folks who work at Children's Hospital and so forth). I could have sworn that it gives admission to the art museums and the history/cultural museums, but now it's looking like they're two memberships? Might be worth a call.