Hi,
<<We have always thought the Silliman Clan came from the English side but no one can get back that far to find out.>>
There were no Silliman entries in British heraldry. It is quite possible that there may be an English ancestry, but that doesn't mean that any of the Sillimans were ever the holders of British arms. The only way you can find out for sure just what your ancestry is would be to trace backwards each paternal generation from your own and ensure that it is done properly and well documented. Could I also direct your attention to a very enlightening article to be found at << http://www.sog.org.uk/leaflets/arms.html >> entitled 'The Right to Arms' It may give you a better understanding of how things work in Heraldry.
Regards,