A person of good moral stature, with a clean record, claiming to have positively indentified marijuana on your property could be enough for a Judge to issue a search warrant. That warrant would have to state that the area to be searched would be outside the home and they would not legally be able to search your house unless they did come across the plants on your property. In which case, the judge would have probable cause to issue a search for your household as well. If the informant in question actually brought plant material as well as the claim to the police, and as I stated earlier had a clean record, that would pretty much guarantee a warrant being issued. The police wouldn't care that the person was trespassing, they would still conduct the search and possible arrest, and you would have to argue the entire trespassing issue in court. If this is some kind of blackmail issue or someone did come across any illegal doings on your part or someone you know, I would suggest getting rid of the evidence, if any, to be on the safe side.
