F&F, we make our own here at the shop, that way we know that they will be there for the long haul.
Simply use the mound in question (we have pics on hand for ref's) as your ref.
Then use a can of "great stuff foam crack filler and insulation" to make your small round pods or balls of dirt. Just test the flow on your can of foam to experiment w the size of your mud ball. Once you get the hang of it , just shoot the mound in the shape and configuration you want.
( the foam doesnt really expand all that much) Ahter about 15 mins it is not tacky and you can control the size of the mound somewhat.
It will be completely set in about 4 hrs. (the instructions say

Once its dry take whatever "DRY dirt you have to use and mix it to a paste consistance w either elmers glue or mod podge and paint it on your mounds. It will keep a wet look this way and will not fall apart.