Can police come on my property with no warrant and take my trailers because they do not have a stamped VIN plate?

They should have had a warrant and the search was illegal. If you haul did not say it was stolen then they overstepped their bounds.

There is clearly a search & seizure issue here. I cannot answer it directly yes or no (did the cops need a warrant before seizing the property ) without more detailed facts and some research into the law. Some questions: if the cop knew the one trailer was stolen (was it ) is it then "contraband" which the cops can lawfully seize. Does he have a right to enter on private property to do so. If lawfully on the property, can he then seize other trailers that he only suspects to be stolen I think there are some real issues here and would encourage you to consult with a good criminal defense attorney. You will certainly need one if/when charges are brought against you (assuming the trailer(s) was/were stolen). These search issues may be the key to a successful defense.