What is the ruling on taking a small amount of soil from a public place or agricultural land to grow ornamental plants at home?

It is forbidden to take from private property except with the owner's permission, and from public property except by its rightful claimant or with the permission of the authorized official. It is obligatory to seek permission to take even a small quantity of soil if it has customary value, due to the general prohibition against taking others' property, unless custom dictates forgiveness in such matters.