From Jam Paper & Envelope. (Both come in a bunch of sizes.)
We're going with "kraft paper" in a fancier stock for our invitation envelopes. These 100% recycled babies will come in handy later when we send the rehearsal dinner invite, etc.
And the map envelopes (made from surplus land maps) are just plain awesome. My little stash from the nyc flagship ran out recently, so I was psyched to find Jam Paper's online store.
(Images courtesy of Jam Paper & Envelope)