No never seen this or done it. They will not expect it. Funeral directors and their staff are from my experience the loveliest people. Concentrate on what you need to do. As Different says hugs if you need them.
I think historically it was traditional to tip the pallbearers provided by the funeral director and the gravediggers. These days I don't think funeral directors expect a tip so don't feel that you have to budget for it. Funerals are expensive enough!
I was involved in arranging two family funerals last week and the funeral director and his staff couldn't have been more helpful or kinder. Please don't worry and don't be afraid to ask any questions.
We didn't 'tip' the funeral directors we used last year.
I had never had to arrange anything like this previously either but they were so lovely & they made the day itself run like clockwork for us. They are totally used to dealing with people who don't know what they're doing & are also dealing with a death so they know exactly how to guide you through & hold your hand whenever you need it.