Most of the US has Class E airspace above 1200 AGL or lower. However, when flying VFR in Class E Airspace, you are not required to monitor or transmit on any frequency, ATC or otherwise. And that includes 121.5, there is no requirement to monitor 121.5.
You may, if you so *choose*, request VFR flight following from the appropriate ATC facility while flying VFR in Class E airspace, but that is completely a choice, as in something you may choose to do or not. There is no requirement to do so.
In that Class E airspace, how extensive is the FAA's surveillance coverage? Does it go down to 1200 AGL or lower?