[Cob] Speaking of free waste materials, might these work?

[Lisa Story]

Hi, all!

I'm new to this list and new to cob building but excited to get  
started on my first project (simple garden walls...then planning to  
move on to an earth oven, tool shed, meditation studio....).

I'm mindful of the benefits of building with locally available  
materials, but here in the Texas panhandle only the clay is really  
local.

But I found this possible alternative for sand--which is really a  
sand derivative: our local recycling center grinds and semi-polishes  
glass in two sizes, "sand" and "pea". It's polished just enough to be  
safe but still has some sharpish edges (i.e., not polished to the  
point of sea glass smoothness). The sand size is like a coarse  
utility sand but has a wider range of texture, from very small  
dustlike particles to peppercorn size. The pea size is more like  
gravel. Both are a lovely eye-catching mixture of clear, green, blue,  
and brown glass that I think would be gorgeous in a raw cob wall-- 
and, of course, best of all, it's just a couple of miles away and  
FREE! Anyone here ever tried this in place of sand or willing to  
weigh in on the advisability of doing so?

Second, straw...about the only thing grown in this area is cotton!  
Cotton waste (organic, even) would be easy to come by in fall--has  
anybody ever tried using this? Another possibility that's not  
terribly local but not too distant is loblolly pine straw, but I'm  
doubtful that this would have sufficient tensile strength. Hand- 
Sculpted House advises against alfalfa, I know, and we have more  
timothy around here, anyway, but I don't know if there's even such a  
thing as timothy straw or, if so, whether it would be usable?

I'm grateful for any opinions and advice on these materials or other  
relatively local alternatives I may be overlooking. Would also love  
to know if anyone here is building with cob in the TX/OK panhandles,  
extreme southeastern CO, or northeastern New Mexico--am looking to  
gain experience and glad to volunteer on any local/semi-local projects.

Thanks,
Lisa