Can Libraries Sell Items For Revenue?

Several of the library's board members feel that it is illegal for the library to sell anything other than books and keep the money. They believe that the library cannot "ask for money". That function (selling items, asking for money, etc) is a function of the Friends group. We (the library board) can accept donations and NYS law indicates that we (the board) can sell books and keep the money but we cannot sell anything else, even if it is a gift basket that contains mostly books.

Is this true? Does this hold true for partnering with another non profit organization nearby who has a small gift shop? Can we (library board not the Friends) supply the gift shop and receive a portion of the profits?

The Friends do raise money for the library but it is difficult to pass this duty on to the Friends because it is difficult for them to part with money for the library board's needs. Hence our desire to do things on our own.

Any help with the rules regarding selling would be greatly appreciated!