Question: What state does Round Table Pizza and Peter Piper Pizza have in common?

Context paragraphs:
Round Table Advertising: Round Table Advertising (Round Table) is a privately held full-service advertising agency located in Toronto, Ontario.  The company was founded as Round Table Advertising Inc. in 2000 by former co-workers Sallah Cayer, Fiona Gallagher, and Brent Peterson.

Round Table: The Round Table is King Arthur's famed table in the Arthurian legend, around which he and his Knights congregate.  As its name suggests, it has no head, implying that everyone who sits there has equal status.  The table was first described in 1155 by Wace, who relied on previous depictions of Arthur's fabulous retinue.  The symbolism of the Round Table developed over time; by the close of the 12th century it had come to represent the chivalric order associated with Arthur's court, the Knights of the Round Table.

Civil War Roundtable: Civil War Roundtables (also referred to as Round Tables or CWRTs) are independent organizations that share a common objective in promoting and expanding interest in the study of the military, political and sociological history of the American Civil War.  The oldest such group in the United States is The Civil War Round Table of Chicago, which was founded in 1941 and is based in Chicago, Illinois.  The second and perhaps third oldest are the Civil War Round Table of Milwaukee (founded in 1947) and the Civil War Round Table of the District of Columbia (founded in 1951).  There are hundreds of such organizations throughout the U.S., with some in other countries as well.

Hillcrest Round Table: The Hillcrest Round Table, or "Comedian's Round Table", was a group of Jewish comedians who met daily at a particular round table at the Men's Grill of the Hillcrest Country Club in Los Angeles.  The group included (from oldest to youngest):

Gandhi–Irwin Pact: The Gandhi–Irwin Pact was a political agreement signed by Mahatma Gandhi and the then Viceroy of India, Lord Irwin on 5 March 1931 before the second Round Table Conference in London.  Before this, the viceroy Lord Irwin announced in October 1929, a vague offer of 'dominion status' for India in an unspecified future and a Round Table Conference to discuss a future constitution.The second round table conference which was held in 1931

East German Round Table: Round table refers to the Central Round Table ("Zentraler Runder Tisch") that convened in East Berlin on December 7, 1989, the day after Egon Krenz, the new head of the Socialist Unity Party (SED) government, resigned.  This Round Table, modeled after the Polish Round Table convened in April 1989, was initiated by the group Democracy Now.  It was set up as a forum in which members of East German government organizations (such as the so-called block parties, trade unions, the women’s league, etc.) came together with representatives of the new citizens’ movements (such as Democracy Now, Democratic Awakening, and New Forum) to discuss and advance reforms in the German Democratic Republic (East Germany), advising the executive until new national elections could be held.  There were 39 representatives at the Central Round Table, 33 with voting rights.  Seventeen of them represented new oppositional groups and political parties, and 16 were from political parties and organizations that had been part of the official East German government.  Three, representing women, consumers and environmentalists, had observer status.  The final three members were the moderators, all clergymen, from the Protestant, Catholic and Methodist churches, who did not have the right to vote.  At first most participants hoped to reform the East German government and thus retain the country’s independence, but as popular opinion moved towards rapid unification with West Germany, these hopes were dashed.

Peter Piper Pizza: Peter Piper Pizza is an Arizona-based pizza chain with locations in Arizona, California, New Mexico, Texas, Oklahoma, Nevada, and Mexico, and formerly in Colorado, Utah, and Michigan.  Restaurants usually have a large dining area that adjoins a game room with playground equipment and classic arcade games.

Menlo Park station: Menlo Park is a Caltrain station located in Menlo Park, California.  The station was originally built in 1867 by the San Francisco and San Jose Railroad and acquired by the Southern Pacific Railroad.  During the 1890s, Southern Pacific added Victorian ornamentation to the depot to make it appear more attractive to students and visitors to Stanford University.  The station was added to the National Register of Historic Places in 1974, and became a California Historical Landmark in 1983.  It is also within walking distance of the oldest Round Table Pizza.

41 Club: 41 Club is the more commonly used and shorter name for The Association of Ex-Round Tablers' Clubs a social networking organisation for men aged over 40 who are also former members of Round Table.  Thus, 41 Club forms part of the Round Table Family of clubs, together with Round Table, Ladies Circle and Tangent.

Round Table Pizza: Round Table Pizza is a large chain of pizza parlors in the western United States.  The company's headquarters are located in Concord, California.

Supporting paragraphs: Round Table Pizza Peter Piper Pizza
Answer: California