I like
Lynn. Something's been keeping me from adding it to my list though.
These might be too feminine sounding, but I'm liking the flow:
Lynn MicaiahLynn JosiahLynn IsaiahLynn Tobiah /
TobiasLynn ZechariahLynn AddisonLynn Emery / Amory
Lynn MackenzieLynn Valentine
Okay. More masculine stuff:
Lynn AlexanderLynn AbrahamLynn ChristopherLynn EliasLynn AtticusLynn OliverLynn SullivanLynn HarrisonLynn EzekielLynn SebastianLynn AugustusLynn ApolloLynn EvanderLynn HadrianLynn Joel (only pronounced JO-el though, not JOLL)
Lynn ConstantineLynn MarcellusLynn MordecaiLynn Silvester
You're right. 1 syllable first names are difficult.
Oh and
Lynn Benjamin and
Lynn Nicholas would have been good, but you can't use those. ;]