Thanks very much, Carolyn and Rita!
>> ... brown paper lunch bags which I leave open for at least a month.
>> Then I roll them up enclosing the seeds,
That saves some time and makes it less likely that you'll lose the label or drop them on the rug while transferring them.
Paper bags must also handle really wet flower heads easier than my method. When I try to salvage seeds during "rainy season", even after pressing out all the water I can, I also let them dry totally open to air movement until they are at least dry-ish to the touch, before bundling them into paper envelopes.
I bought a bundle of "school lunch sack" paper bags, but I manly use those for sorting outgoing seed-trade packets. Sometimes I collect big, bushy plant limbs with seed pods in a big, grocery-store-size paper bag, or a big cardboard box.
But then I try to reduce the bulk so that the pods or seed-heads will fit into an envelope. Luckily, I get a few things in the mail in rather large envelopes, so I have some options.
I bet that humidity migrates even faster through thin Kraft paper bags than through glossy, heavy paper envelopes. And of course the open top of a paper bag allows total air circulation.
>> which I leave open for at least a month.
Yes! No matter how open a container is to humidity diffusion and air circulation, nothing can ever dry drier than the average humidity of the air it is exposed to. In my house that seems to be 50% RH (at least it is inside sealed seed jars).
And the speed of drying slows down to zero as the equilibrium RH of the seeds approaches the average RH of your household.
When I read that 50% RH is just "napping" for seeds, not "deep sleep" or "hibernation", I was sure that I needed desiccants if I wanted maximum viable lifetimes and rapid drying down to 15-30% RH. Of course, how many seeds do I save unused for more than 5 years and then have a burning desire for high germination rates? ... A few!
Frugal? I only feel frugal when I cut envelopes in half so I can have twice as many for free! And then I begrudge the Scotch tape on the cut edge!
P.S. I love envelopes with a clear glassine window. Then I can see my precious seeds while they sit on the table.