Question: What type of organization does Mellow Mushroom and Gatti's Pizza have in common?

Context paragraphs:
Shiitake mushroom dermatitis: Shiitake mushroom dermatitis (also known as "Flagellate mushroom dermatitis," "Mushroom worker's disease," and "Shiitake-induced toxicoderma") is an intensely pruritic dermatitis characterized by disseminated 1mm erythematous micropapules seen in a linear grouped arrangement secondary to Koebnerization due to patient scratching.  It is caused by the ingestion of shiitake mushrooms and was first described in 1977 by Nakamura.  Although it is rarely seen outside of China and Japan due to a lower incidence of shiitake consumption outside these regions, there is a well-established association between flagellate dermatitis and shiitake mushroom (Lentinula edodes) ingestion.  Bleomycin ingestion may also cause similar findings.  On physical exam, one key difference between the two is that post-inflammatory hyperpigmentation changes are usually seen with bleomycin-induced flagellate dermatitis and are not typically present with shiitake mushroom induced flagellate dermatitis.  The median time of onset from ingestion of shiitake mushrooms is typically 24 hours, ranging from 12 hours to 5 days.  Most patients completely recover by 3 weeks, with or without treatment.  Although the pathogenesis of shiitake induced flagellate dermatitis is not clear, the theory most argued for is a toxic reaction to lentinan, a polysaccharide isolated from shiitake mushrooms. However, Type I and Type IV allergic hypersensitivities have also been supported by the 24-hour median time of onset, clearance in 3–21 days, severe pruritus, benefit of steroids and antihistamines, and lack of grouped outbreaks in people exposed to shared meals containing shiitake mushrooms. Most cases reported shortly after its discovery were due to consumption of raw shiitake mushrooms, but several cases have since been reported after consumption of fully cooked mushrooms.

Agaricus silvaticus: Agaricus silvaticus (or Agaricus sylvaticus), otherwise known as the Scaly Wood Mushroom, Blushing Wood Mushroom or Pinewood Mushroom, is a common, edible Mushroom, often found in groups in coniferous forests from early summer, or September through to November in Europe, North Africa and North America.

Gatti's Pizza: Gatti's Pizza (formerly Mr. Gatti's) is a Southeastern United States pizza-buffet chain.  Gatti's Pizza, founded in 1964 is owned by Blue Sage Capital, a private equity investment firm.  The corporate offices are in Austin, Texas.

Mushroom poisoning: Mushroom poisoning (also known as mycetism or mycetismus) refers to harmful effects from ingestion of toxic substances present in a mushroom.  These symptoms can vary from slight gastrointestinal discomfort to death.  The toxins present are secondary metabolites produced by the fungus.  Mushroom poisoning is usually the result of ingestion of wild mushrooms after misidentification of a toxic mushroom as an edible species.  The most common reason for this misidentification is close resemblance in terms of colour and general morphology of the toxic mushrooms species with edible species.

Hydnum repandum: Hydnum repandum, commonly known as the sweet tooth, wood hedgehog or hedgehog mushroom, is an edible mushroom with no poisonous lookalikes.  A basidiomycete fungus of the family Hydnaceae, it is the type species of the genus "Hydnum".  The fungus produces fruit bodies (mushrooms) that are characterized by their spore-bearing structures—in the form of spines rather than gills—which hang down from the underside of the cap.  The cap is dry, colored yellow to light orange to brown, and often develops an irregular shape, especially when it has grown closely crowded with adjacent fruit bodies.  The mushroom tissue is white with a pleasant odor and a spicy or bitter taste.  All parts of the mushroom stain orange with age or when bruised.

Mellow Mushroom: Mellow Mushroom Pizza Bakers is a restaurant chain that was established in 1974 in Atlanta, Georgia as a single pizzeria.  It operates as a franchise under the banner of Home Grown Industries, Inc. of Georgia, with over 150 locations throughout the United States.  Its headquarters are in Atlanta, Georgia.

Panaeolus foenisecii: Panaeolus foenisecii, commonly called the mower's mushroom, haymaker or brown hay mushroom, is a very common and widely distributed little brown mushroom often found on lawns.  In 1963 Tyler and Smith found that this mushroom contains serotonin, 5-HTP and 5-hydroxyindoleacetic acid.  In many field guides it is listed as psychoactive due to psilocybin content, however the mushroom does not produce any psychoactive alkaloids.

Cream of mushroom soup: Cream of mushroom soup is a simple type of soup where a basic roux is thinned with cream or milk and then mushrooms and/or mushroom broth are added.  It is well known in North America as a common type of condensed canned soup.  Cream of mushroom soup is often used as a base ingredient in casseroles and comfort foods.  This use is similar to that of a mushroom-flavored gravy.

Hericium erinaceus: Hericium erinaceus (also called lion's mane mushroom, bearded tooth mushroom, satyr's beard, bearded hedgehog mushroom, pom pom mushroom, or bearded tooth fungus) is an edible and medicinal mushroom belonging to the tooth fungus group.  Native to North America, Europe and Asia it can be identified by its long spines (greater than 1 cm length), its appearance on hardwoods and its tendency to grow a single clump of dangling spines.  "Hericium erinaceus" can be mistaken for other species of "Hericium", all popular edibles, which grow across the same range.  In the wild, these mushrooms are common during late summer and fall on hardwoods, particularly American beech.

Pholiota squarrosa: Pholiota squarrosa, commonly known as the shaggy scalycap, the shaggy Pholiota, or the scaly Pholiota, is a species of mushroom in the Strophariaceae family.  Common in North America and Europe, it is often an opportunistic parasite, and has a wide range of hosts among deciduous trees, although it can also infect conifers.  It can also live as a saprobe, deriving nutrients from decomposing wood.  The mushroom is typically found growing in clusters at the base of trees and stumps.  Both the cap and the stem are covered in small, pointed scales that are pointed downward and backward.  The crowded gills are yellowish, then later rust-brown.  The mushroom has an odor that, depending on the author, has been described as resembling garlic, lemon, radish, onion, or skunk.  It has a strong taste, resembling radishes.  Once thought to be edible, it is now considered and known to be poisonous, especially if consumed in combination with alcohol.  The mushroom contains unique chemicals thought to help it infect plants by neutralizing defensive responses employed by them.  The very similar "P. squarrosoides" differs in having a paler cap that is sticky between the scales, and smaller spores.

Supporting paragraphs: Mellow Mushroom Gatti's Pizza
Answer: chain