Paul might say nettles
along with hemp, rami, flax, jute and kenaf are what are called bast fibers, meaning the fiber comes from the stem of the plant. The likely one to grow in th US to replace jute for burlap would be nettles I guess but I don't have any first hand knowledge. Flax along with hemp and maybe all bast fibers don't need super fertile ground or have problems with pests
. For some reason linen (flax) yarn was extremely expensive when I was weaving with it. Most of the processes for making bast fibers into yarn/twine are either very labor intensive or use chemcal means to achieve the end product.
I am glad you brought this up, I had been wanting to research nettles as a fiber and this reminded me to do it.
What are you using burlap for? I've found uses for coffee
sacks when we have had them but not on a regular basis.