This is a common problem that we remedy by placing stonework around the collar of the drain inlet.
You can get as fancy or rustic with the stone work as long as it allows water to still filter in and debris from clogging the inlet.
The stones are set in a dry lay pattern - no mortar and usually never a footing.

We've even intergrated these into a dry river pattern of stone work with large boulders meandering the outer edges and smaller rock in the dry creek. .

Do you intend to plant groundcover in the mulched area? Such plants would hide the drain completely and help stabilize the ground surrounding the drains and act as a filter so that soil and bits of flotsam were not washed into the inlets. You'd need to periodically trim it back so that it didn't actually cover the drains.

Do not set rocks on top of the grate.

Thank you for your comments! Deviant-deziner, if you have a photo (or a link to one) of what your talking about that would be a huge help. Yardvaark - i that's a great idea too. I could plant a ground cover...
I hugely appreciate this!

Most all of the photos that I have of the drain is obscured by the rock placement.

Here is a quick sketch of a simplied rock placement.
As long as the rock has enough space between them to allow for the sheet flow of water you'll be find.
This is actually a duplicate rough detail from a soils engineers office.