Almost all of my friends collect different things, and they all know other people that collect all sorts of things. The trick is to start talking to friends or other worthy people now to get some ideas about where to leave your stuff after you are gone. Your next door neighbor may love old lace tablecloths, or maybe her grand daughter does. Someone you work with might collect craftsman era chairs or lamps, or maybe their neice does. Start conversations with people that you like and love and tell them your story, you’d be surprised by how many people that you know, or people close to those people, collect and love all sorts of things.
The other alternative is to speak with a representative at either a historical society, either in the town where you live, or in various towns from where the items originated, and see if they are interested and able (make sure it’s both) to not only accept the item, but to make sure that it is cared for and not simply sold off as a fundraiser (unless you’re OK with that).
Another alternative is to talk to other charitable organizations to whom you would like to donate and again, be very specific when you talk to the representatives to let them know that you have items that you would like to donate, either for them to keep or for them to auction off to make money. Just be clear about what you want the organization to do with your donation and if they’re able to accomodate you.
Some libraries and colleges also accept donations of items in a collection, to put on display. Ask around and see if this is something that you might be interested in doing.
And of course there are museums (other than historical society organizations) that might be willing to accept some of the items. Just be very clear with them (in a contract with your donation upon your death) whether you want them to keep the item in their collection, whether you expect it to be put on display, or whether you are willing to let them sell the items at auction, to purchase other items that are better suited to their specific collections. The registrars and curators at museums are the people that you want to talk to first. You also should talk to some type of lawyer that handles your will or living trust to help you choose the right kind of contract and “last wish” instructions for your will or trust. And then, let your SO or anyone else who needs to know, what your plans are, so it doesn’t come as a big surprise at the end. : )