Many herbs, including those you mentioned but with the notable exception of garlic, onion and other plants, are considered to be non-toxic and edible in small amounts. Some of these plants do contain varied amounts of volatile oils, resins and/or tannins, which can all irritate the GI tract. The oils can even cause central nervous system depression if consumed in large amounts. The bottom line? A nibble or two of an herb such as lavender, rosemary or sage is not likely to be an issuebut don’t let your cat munch on these herbs in large quantities.