I have the following:
12"x15" manilla envelope [0ne]
12.5"x18.25" manilla envelopes, with corrungated cardboard [nine]
17"x22" manilla envelopes, with corrugated cardboard [three]
at least one plastic envelope from Studio Art, used to transport 32"x40" pieces of mat board
Since I doubt that they are acid-free, none of these envelopes are for long term storage of photos, but I would be happy to pass them to anyone who would like them. The corrugated cardboard pieces came with the envelopes and were used to keep the photographs straight.
Most once housed my enlargements from Stubblefields, but the current owners aren't interested because they feel their clients would use them for long term storage.
