By going up to the side of the thing and laying down in the grass and peering in.

Hmm... How silently can he do this?

It's not like he has to crawl through a bush, he can just tiptoe up through grass.

She has super hearing though.

He'll try anyway. Veeery slowly.

The scraping continues.

From his new (still limited) viewpoint, she appears to be scraping large quantities of the moss growing on the back wall of the masoleum and collecting it into a big bowl.

...what. Why.

Also, the moss seems to be glowing softly yellow.

What the duck.

Is it all the moss or is it just the moss she collects or...?

It starts glowing as she collects it. The bowl is awash with light.

She stops scraping, tilts her head as if listening.

He holds his breath and holds as still as he possibly can.

After about fifteen seconds, she seems to decide to cut and run. She is almost but not quite as silent as last time as she makes for the exit.

Can he watch where she goes while making as little sound as he possibly can and remaining hidden?

Probably not, this would require turning around and standing up on the grass!

Okay he can just wait then.

She's gone.

A finger-size piece of the gold glowing moss was left behind in her hurry to leave.

Well then. He wants to collect it.

And try to collect some not-gold not-glowing moss to see if it turns gold glowing.

The gold glowing moss continues to glow when he picks it up. The non-glowing moss stubbornly continues to not glow when he scrapes at it.

...is there any possible indication of why it may be glowing? Is it any different than the non-glowy moss in any way other than, you know, glowing?

Nope!

...weird. He... wasn't expecting to be holding glowy moss so he doesn't have a container but he can store it in his backpack for now and start back home, being careful to be quiet and lock the place.

When he gets home, he notices that he's not tired. At all. It's like he's had four cups of coffee in the last hour or something.

...well then.

He has an old microscope kit, the kind kids have to play with, somewhere. He's quiet enough while he searches for it and eventually, there it is. Any detectable differences between the moss?

The sample he scraped up himself is just the body of the moss. The glowing one has some kind of undermaterial.

Also, the glowing moss seems to be slowly stopping glowing.

No no no no what's the undermaterial—

The undermaterial looks like... Dirt... Or roots?