It can be possible to get a US work permit if you are married to someone resident in the States but this depends on their status. Citizen or those holding certain sorts of visas. Those without work permits are often effectively prohibited from volunteering, a real bore for ex-pat spouses.
However:
- It takes at least three months for the US to process the paperwork.
- There is enough in Aimee's past, including that weird stuff that happened in Birmingham when they are about 15, to jeopardise even residency let alone a work permit. (Too lazy to look it up, and don't want to break MN rules. I assume US immigration use google, and having your personal information collated by the Farmers is not good news.)
If Aimee does not have residency, boasting of donating to US politicians is not a good move. I note that allegations of Russians trying to influence the election in favour of Trump are resurfacing. Other foreigners, with interesting backgrounds, donating (albeit threepence ha'penny) to Warren is a potential gotcha.