Fundraising in Public Libraries

I have always been under the impression that it is illegal for public libraries to fundraise on their own, aside from 2 book sales per year. If a school district public library no longer has a Friends Group, can it host fundraisers? For example, could the library itself host a bingo night and raise money? Can a school district public library send out a fundraising letter?

Or is it important that all library staff and trustees refrain from fundraising efforts in order to separate public funds from fundraising? I am struggling because we have a lot of great ideas, but the future of our Friends Group is unclear. I am wondering what options are available to me as a library director, and my Board of Trustees, if the Friends Group were to dissolve.

Thank you so much.