You have to read labels - many mousses have silicones, just like many gels and other styling products.
Lots here use Got2B mousse
- is CG, cheap, and at any drugstore (it has one PEG-modified water soluble 'cone more than halfway down the list) and works well for me, so it's in my occasional
rotation. It contains castor oil which doesn't agree with my hair if I use it all the time, but many love it. I still use a bit of gel on top of it for additional hold.
They also have this new one
I 'heard' somewhere here is supposed to be good, but I haven't tried it (drugstore.com or Walgreen's didn't have it on their sites). The ingredient list looks the same as for the other one, so I wonder if it's actually been updated for this new version.
is CG and liked by mousse users, but it's more costly. I used to use and like it when it was called Joico I.C.E. Whip, but have just pretty much gotten away from mousse since then except for the occasional use of Got2B - too many other things to play with, LOL.
Herbal Essence mousses are CG and some like them, but I hated Totally Twisted. Made my hair a tacky, sticky mess, so I never tried any of their other formulations.