Cops don't usually call first before making a raid...but if you had them sent to your grow room, then I suggest you play it safe and make sure there's nothing that'll get you busted for possesion or intent to grow.

Did you call the number back to see what department it was? Could have just been a political pollster.

If worst comes to worst, simply deny everything. Convince them you are too stupid to even buy seeds in the first place. Tell them you had ordered a cool looking pot poster and assholes sent you something else.