You did the right thing. I feel that it's inappropriate to take money from pts or family. If you happen to run into her just say that you appreciate the gesture but its against company policy. I've been offered money before as well but have adamantly declined. If people feel they should give something say that we always appreciate cards, a note to our managers, and always food to the entire unit as a gift if they feel the need! But I wouldn't stress about it. If somebody had found out and you didn't tell it could've gotten messy.