I am by no means an overly neat and tidy gardener. I like my plants to interact but this is one thing that drives me crazy. We have a big Brazilian Pepper tree in the back yard in SJC and they are notoriously messy. Near the very edge of the drip line in another level of the yard altogether is a large stand of yuccas and green agaves that is the cornerstone of a garden bed that I am developing. Those agaves always look like they need a good cleaning, which they get often, but they still always look like the picture above.
I would think that the debris would hold in the moisture and eventually rot the agave but that doesn't seem to be the case. I'm not about to remove the tree and the agaves aren't going anywhere soon, so I guess I had just better start thinking of them as little compost bins. But I will note the lesson learned here. Watch what you plant around some of these messy, messy trees.