To Give or Not to Give
Should you expect guests to bring gifts to a reception given weeks after the wedding? Well, let's back up and cover the rules of traditional etiquette here. You should never
I Want That!
You cannot request a particular gift. Don't try to do it unless someone specifically asks if you need or want something. For example, it's in the worst taste to announce that you are only accepting money for your wedding, no matter how desperately you don't need anything except cash.
E~Fact
You can ask your mother or grandmother to spread the word that you'd really appreciate monetary gifts, but they have to be able to do so with some subtlety. In other words, having your mother tell the relatives to break out their checkbooks is not acceptable.
You also can't slip those little registry cards into reception invitations (a practice that etiquette mavens have always found to be in poor taste anyway, even when they're placed inside the shower invitations). The whole idea behind gift-giving is that it's supposed to be as much fun for the giver as for the recipient, but this assumes that the giver is an avid shopper who loves to browse stores for the perfect wedding gift. This isn't always the case, and many times, it's just easier for people to give money or for them to look up your registry. Again, have your mother and other close relatives spread the word about your registry.
Don't Be Greedy
The problem with after-the-fact receptions is that they are sometimes seen as an opportunity for the bride and groom to cull gifts from people they didn't want at their wedding in the first place. You can put these suspicions to rest by acting the part of the gracious newlywed couple during the reception. Make sure to speak with

