Busy 1-St Day Cover 10/19/31 Event Wash DC + Suprise

I found this browsing my accumulation of STUFF...

Bush Cover:

1. Arthur K Roberts was a participant in or around the West Coast
Lumberman's Association.
2. It is a First Day Cover 10/19/1931
3. It is mailed from an event in Washington DC
4. It has a note enclosed with an event program

Suprise:

5. It is a 2c Washington embossed stamped postal stationary envelope
(they put the Scott#703 2c stamp right over the embossed stamp)

note: many articles on Mr Roberts on search of Google

Hard up for envelopes, and used what was handy?

Depression era could be.

I think the more likely reason for using an embossed envelope was that it could quickly be purchased at the post office where the new stamp was being postmarked with the FDOI cancellation. Perhaps the person was not planning to attend the ceremony or happened upon it not realizing that FDOI cancels were being offered, which resulted in the need for a quick purchase of an envelope in order to secure the cancellation.