ok i got some links for you....
i am a member of garden web seed exchange and i have done some excellent trades there =)
if you were to sign up, as a newbie many people will post with SASE or SASBE (self addressed stamped envelope, or bubbly envelope) and will send you starter packs for stamps.. and although it is not allowed to just post and ask for free seeds, many members do generously donate free seeds, in the form of a sase offer. also if you get yourself some cheap/harvested seeds somewhere, and then offer them for trade stating your a newbie, people usually respond well and will trade what you have for what you want.
just saw this one this morning, i have actually donated to this woman before, she does a great job every year with hooking people up with free seeds to start off
http://forums2.gardenweb.com/forums/load/exseed/msg121921343895.html?10
some more
http://www.wintersown.org/wseo1/Free_Seeds.html