Trying to rediscover an author

[Darkfalle]

When I was much younger I remember reading a collection of short stories, they may or may not have all been by the same author. In any case, they all fit into the category of weird fiction. One of them involved unusual postage that came from an unknown country. When affixed to an object, the stamps literally caused it to fly away. Another involved a character traveling back in time to (I think) the French Revolution as a goose.

Anybody have any ideas?