Most of the ones on Roberts were put there by the Corps of Engineers and they are huge. Most at Lewisville were built by fishermen and are much smaller but there are hundreds of them. Also lots of underwater trees still standing. You just have to spend some time finding them.

I have an old school depth finder and have only found a couple of brush piles on Lewisville. One day i hope to upgrade my electronics so i can find them easier.

I went there Saturday and caught one crappie at a bridge pillar
I couldn't find a brush pile at all. But then again it was my first time there with a new boat and graphs I have never used.
How the heck do you find a brush pile on a huge lake?

Or course the best way is to build and place your own, but if you are on new water, the best way is to sit down with a lake topography map and look at likely areas for crappie. Points, steep drop offs, coves. Also look for an area that have those features on the leeward side of tree lines that will block the prevailing wind. Then look in the water depth range for that time of year. On the structure that I have placed, it was actually hard to find a place that didn't already have something there. I have added to some because it was just too good of a place to put it elsewhere.

First you find a brushpile and run over it repeatedly from different angles until you know what to look for. Then follow almost any shoreline in 15'-18' depth range and you should find lots of them. I know of almost 200 on Lewisville and I'm sure there's a lot more. Shorelines that are protected from south winds have more but there's lots on the north side also.

One problem right now is that there's so much bait in the water that they hide the piles. If you have sidescan it's really easy to find them.