Well, unfortunately, the siren graveyard in Wichita, KS is no longer there it was a temporary site for storing the sirens the EMA then moved the location of the sirens. I do not believe that there are any siren graveyards near Nebraska. The one main graveyard that everyone knows about is West Shore Services in Allendale Michigan. They are the Federal Signal representative for Michigan and a lot of the other parts of the US. I heard recently that they are not so big on the tours any more though. Although if you are a serious buyer looking for a used siren I think they may let you come look around. Hope this helps.
Also I know how frustrating it is to look on google maps for siren locations so here is the link to the site in Wichita where they used to keep the old ones:
https://www.google.com/maps/@37.7813512 ... 6656?hl=en
Proud owner of rcm1, model 2,2T,Model A, Thunderbolt 1003, AF timer, FS SS1000, 500SHST
Wisconsin siren services
https://www.swssirens.com