There's a Cantonese restaurant in Mountain View, CA called Fu Lam Mum -- the characters are clearly 富臨門.
But 門 has always had a -n final, in any topolect I know of, and back to MC and OC according to Baxter's reconstruction. Therefore this must be a sound change (assimilation at a distance) in a daughter language.
In what topolect, if any, does 門 have an -m final? Being a Cantonese restaurant in the US, I'd suspect Taishan, but that's just a guess.