I'm going through my stash and getting ready to sell/give some away and I had a question about mailing it. I've got 9" x12" brown envelopes to use and plastic bags to protect the fabric in case the package gets wet. Do I need to wrap the fabric around any type of cardboard/cardstock or do I just neatly fold the fabric & slide it into the envelope? Thanks!

I don't think the cardboard/cardstock is necessary, it will just increase the shipping cost :D:D:D

I would just put it in the envelope. I usually use padded envelopes, however. They seem sturdier to me.

For fabric I prefer to use the padded envelopes or the tyvek ones. Wrapping your fabric in plastic is a good thing. And be sure to put a copy of the TO and FROM addresses inside the bag with the fabric. If the envelope gets destroyed or wet, the address is still preserved inside.

EDITED TO ADD - Fabric can get really heavy for mailing. I think that most of us use the Flat Rate envelopes from USPS for more than just a bit of fabric.

you can go to the post office and ask for tyvek envelopes- they will give them to you- they are sturdier-
the problem with just using manilla envelopes is they tear really easy- and the postal workers are not really known for their careful handling of packages. the tyvek envelopes may actually weigh less too.
or padded envelopes are also good to use for sending (squishy's)
the ones you have really are not (built) for squishy- they are better saved for documents...flat

I recieve from Oklahoma Quiltwork BOM and they just place the fabric in a plastic bag and in a yellow envelope. I have yet to recieve anything damage.

I use the flat rate boxes from the P.O.
If I use an envelope I agree with the other responders - get the padded ones

The weight limit on First Class large envelopes is 13 oz and that costs $3.28. If you're sending up to that weight (about 3½ yds), I'd skip the flat rate option at $4.95 as a waste of money.

If you are planning on sending out a lot of fabric, it is worthwhile to buy a scale - saves having to go to the post office -

It is more economical to send mail by First Class up to 13 ounces.

I don't use a cardboard in the fabric I mail out. I haven't heard about any problems with shipping. I also put the fabric in a plastic bag before putting it in any envelope.

Envelopes are usually cheaper than the flat rate envelopes.
Judy