How does one tactfully ask for donations at a funeral for the widow?

What will the donations be for?

Most funeral homes have envelopes for donations, often with a small sign or note by them asking that funds be given to this charity or something.

There is really no good way of asking for money at a funeral. If there is a need, why not call up family or friends and ask them for it

I think you should be able to ask the funeral director for some ideas and possibly help.

I would suggest that you not ask for money at the funeral - it's not the right time or place. Instead you should spread the word to family and friends using email, letters, phone calls etc that a fund is being started for the widow's benefit. Be sure that it's all above board - i.e, establish a bank account specifically for this purpose, and follow up with a note to all donors thanking them and letting them know how much was collected. Do not try to represent this in any way as a charitable fund, because it's not - these are personal gifts to the widow.