If you're doing a city underground, Gabriel's set one, that Kevin mentioned would be great to combine with the mushroom set you've already purchased. Just a suggestion: Make sure when you open the map editor here, you click on the map/background layer. Bring in the city map section(s) on a page, and then do a search for the mushrooms in your library. Gabriel's work has partial transparencies on his shadows so you can place them right on top of the city sewer/dungeon. You don't have to stay on the grid either: When you drag over a mushroom you can hold ctrl+alt to break free of the grid. Holding those two keys, you can also resize the mushrooms off the grid to make a much more elaborate effect, as well as rotate to a specific angle. The Roll20 editor layers pretty easily from back to front, and by right clicking, you can bring items to front or to back really quickly. It may take some practice, but Hope those suggestions help, Devlin.
