The divet gets filled in with mortar. The pea gravel is just a handful to keep the mortar from filling in the weep holes. Look at the picture on the main page of this web site under how to build a shower pan. There harry has arranged a few tile spacers to do the same thing. The straws actually do the same thing, keeping the mortar out of the weep holes. Once the mortar has set the straws are removed and no pea gravel is necessary at all.

Awesome. I checked out the picture. I get it.
This has been great help.