Dry pine needles are cool.
I raked them into a pile and ran the lawn mower over them a few times to chop them into little pieces.
I made a pretty nice pot with those and it seems quite light and strong.
I had to keep misting the curing pot often as the dry needles wicked moisture during curing.

I've used coir and paper pulp as substitutes. I didn't like either working with or the finished result of the coir. I won't use it again. The paper pulp was great to work with. I've used two different types, fine shred from our paper shredder and bulky recycled stuff used for small rodent bedding. Each worked well and I'm planning on using them more in the future. If you try paper pulp be sure it's water logged before using it. Soaking it for several days ensures that it's fully hydrated. If your using shredder leftovers soaking it will also help remove the stuff used to give it a smooth sealed surface.
I've had a friend try straw, shredded mulch and peanut hulls in her 'tufa. I didn't hear any complaints about any of them. Try tumbleweeds and see what how it goes. Are you planning on chopping them with a mower? Maybe that would help break up the little stickers.

Thanks for the input. I think I will try the tumbleweeds and mash them up best I can. Don't have a mower, mostly zeriscape in this part of NM (no snow shovels or blowers either!).

I live near Belen, kind of in the middle of the state...

It's nice to see someone else from NM on the forum.

Where do you live?

Jo