Hi guys! I'm a newbie and I came across these tomestones of poetics. Could anyone give me advise on how best to spend them?

I'm currently a level 47 DRG and I've read that I can spend them on level 50 gears. Are they worth it? Can I spend them on anything else? I haven't reached the place where I can spend them on (Mor Dhona or something I think?) so I haven't been able to check. I got them as rewards from the beast tribe dailies (sylphs etc.)

Thanks!