They did not do anything because they did not have "right's" to be in your yard and observe the plants. They were chasing a suspect whom ended up in your yard, they are allowed to chase into private property.
Even if you were doing lines off an illegal immigrants ass while waiving your black market AK in the air when they came in. They probably would have taken you to jail but you would walk out the same day and the charges would never stick.
They were probably discussing if they can see the plants or smell them without being inside the yard so they could attempt to pursue you.
Find a collective in your area, allot of good people will rescue plants in need of a temporary or permeate home.