I recently came across what I hope to be the 'real' thing.. Can anyone describe/explain how to tell if its an actual 1930's feedsack??

"real" vintage feed sacks will still have the holes along the edges where the heavy string was used in a chain stitch to keep the bag together. even after washing, these holes usually still show. and vintage fabric has a different "feel". not quite as smooth as today's fabrics. we used to go with Dad to the feed store to "pick out" the fabrics we wanted Mom to sew for us. Shows my age, but fond memories.

its courser than what you buy today. and my dad also took me to pick out the fabric for my school skirts.

They look a lot like the fabric that my grandmother had from that era.

I have some that I bought a few years ago with intent to make a quilt like my grandmother always made.
What Smitty said about the holes and coarseness is the best way to tell.
Moda has a line of fabrics that look of this era, as well, if you need some fill-in fabrics.

Looks like you hit the jackpot to me!

Your pieces look alot like the ones DD has in her stash. I would say, "yes".

they feel pretty thick. almost denim-y but not as stiff as denim..

I got a nice size box filled with big chunks and strips of this fabric and another box filled with the same 'type' of fabric but in off white/beige...

The off white beige was used for different things but still it's considered feed sacks. Planting grains such as wheat and hay seed were often sold in the white sacks, some of the smaller ones had sugar and flour in them. Animal feed was usually in the printed sacks. They are all still grouped in what's refered to as "feed sacks". The fabric that you posted looks to be authentic. The weave looks right, the thicker thread used looks right. Sometimes the holes along the edges have been cut off so you can't always use that to go by. If they're there it's easy to tell. If not then you have to look at the weave, the threads and the "feel" of the fabric. Even then depending on the company, the feed, etc., the fabric varied. Some of it was coarser than others but none of it was the quality that you find in the reproductions of today. Looks to me like you've hit upon a jackpot, congratulations. BTW, these fabrics wear like iron.

AS I was rummaging thru the other boxes this morning I found a few more!!! Whoo hoo YAY!!!

That must have been fun; shopping for school clothes at the Feed Store.