The San Francisco Exposition of 1939 to 1940 was held at Treasure Island, an artificial island constructed on the San Francisco Bay between the cities of San Francisco and Oakland.

Brass, 31 mm, 11.12 gm
Obverse:
Airplane flying over Golden Gate Bridge
GOLDEN GATE INTERNATIONAL EXPOSITION / 1939 / SAN FRANCISCO, CALIFORNIA
© (Copyright)
Reverse:
Airplane flying over San Francisco - Oakland Bay Bridge, ferry boat below
SAN FRANCISCO - OAKLAND BAY BRIDGE / 1939 / ON SAN FRANCISCO BAY
© (Copyright)

Brass, 26 mm, 5.86 gm
Obverse:
Golden Gate Bridge, sunset, fair building
GOLDEN GATE INTERNATIONAL EXPOSITION
1939 / SAN FRANCISCO BAY
Reverse:
Tower, modern ship, sailing ship, hills, sunrise
THE TOWER OF THE SUN
157C (Type number)

Brass, 31 mm, 10.52 gm
Obverse:
Golden Gate Bridge, sunset, fair building
GOLDEN GATE INTERNATIONAL EXPOSITION / 1939 / SAN FRANCISCO BAY
PATENTED C110010
Reverse:
Airplane, Golden Gate Bridge
Compass letters 'W', 'N', 'E', 'S' around edge
L-50-lC
CHINA CLIPPER

Brass, 32 mm, 10.89 gm
Obverse:
Woman holding two hands up, Treasure Island
GOLDEN GATE INTERNATIONAL EXPOSITION / 1939
Reverse:
MILENS TREASURE ISLAND SOUVENIR DIVIDEND
THIS LUCKY COIN ALWAYS GOOD FOR $2.50 TO $50.00
AS 10% FIRST PAYMENT ON ANY DIAMOND PURCHASE
BRING IT TO
MILENS JEWELERS 1211 WASHINGTON ST. OAKLAND

Brass, 32 mm, 10.46 gm
Obverse:
Woman holding two hands up, Treasure Island
GOLDEN GATE INTERNATIONAL EXPOSITION / 1939
Reverse:
MILENS TREASURE ISLAND SOUVENIR DIVIDEND
THIS LUCKY COIN ALWAYS GOOD FOR $2.50 TO $50.00
AS 10% FIRST PAYMENT ON ANY DIAMOND PURCHASE
BRING IT TO
MILENS JEWELERS 1211 WASHINGTON ST. OAKLAND

There is a hole in this item, it might mean that the item was used and cancelled.

Brass, 32 mm, 10.54 gm
Obverse:
Golden Gate Bridge, sunset, fair building
GOLDEN GATE INTERNATIONAL EXPOSITION
1939 / SAN FRANCISCO BAY
G.C.I.E. / 140.C (Golden Gate International Exposition number)
Reverse:
Airplane flying over covered wagon
1849 1939

Brass, 30 mm, 9.80 gm
Obverse:
Golden Gate Bridge, sunset, fair building
GOLDEN GATE INTERNATIONAL EXPOSITION (Incuse lettering)
1939
SAN FRANCISCO BAY
PAT. D110016
Reverse:
Treasure Island map
TREASURE ISLAND

Brass, 32 mm, 11.86 gm
Obverse:
Golden Gate Bridge, sunset, fair building
GOLDEN GATE INTERNATIONAL EXPOSITION / 1939
SAN FRANCISCO BAY
PAT. D110016
Reverse:
Treasure Island, airplane, sunset
TREASURE ISLAND

I have two items of this type, this one is in better condition than the one below.

Brass, 32 mm, 11.72 gm
Obverse:
Golden Gate Bridge, sunset, fair building
GOLDEN GATE INTERNATIONAL EXPOSITION / 1939
SAN FRANCISCO BAY
PAT. D110016
Reverse:
Treasure Island, airplane, sunset
TREASURE ISLAND

This item is the same as the one above but is in worse condition.

Aluminum, 32 mm, 3.32 gm
Obverse:
Golden Gate Bridge, sunset, fair building
GOLDEN GATE INTERNATIONAL EXPOSITION / 1939
SAN FRANCISCO BAY
Reverse:
Two railroad engines, shield logo of Union Pacific
ROAD OF THE STREAMLINERS AND THE CHALLENGERS / UNION PACIFIC
UNION PACIFIC - THE OVERLAND ROUTE
ALUMINUM IN THESE FAMOUS TRAINS FURNISHED BY
ALUMINUM COMPANY OF AMERICA

Brass, 31 mm, 10.18 gm
Obverse:
Golden Gate Bridge, sunset, fair building
GOLDEN GATE INTERNATIONAL EXPOSITION / 1939
SAN FRANCISCO BAY
GGIE 140-C
Reverse:
SILVERS CREDIT DEPT STORE
418 11TH ST. - OAKLAND
GOOD FOR $2.00 ON NEW ACCOUNT PURCHASE OF
MEN'S OR WOMEN'S CLOTHES OR JEWELRY OF $20 OR OVER

Bronze, 58 mm, 32.60 gm (2-1/4 inch diameter)
Obverse:
Indian Head
LUCKY PENNY
Reverse:
City skylines, Treasure Island, Bay Bridge
BERKELEY. OAKLAND. / WORLDS FAIR. / SAN FRANCISCO.

Bronze, 35 mm, 13.57 gm
Obverse:
Oil drilling derrick
GOLDEN GATE INTERNATIONAL EXPOSITION
PETROLEUM EXHIBIT / 1939
Reverse:
A DOLLAR SPENT / FOR PETROLEUM PRODUCTS
NEVER STOPS CIRCULATING
IT PAYS FOR WAGES, TAXES, / MATERIALS AND BRINGS
COUNTLESS BENEFITS TO / EVERY BUSINESS

The Petroleum Exhibit was sponsored by the Standard Oil Company of California.

Bronze, 35 mm, 13.45 gm
Obverse:
Oil drilling derrick
THE STORY OF PETROLEUM
GOLDEN GATE INTERNATIONAL EXPOSITION / 1940
Reverse:
A DOLLAR SPENT / FOR PETROLEUM PRODUCTS
NEVER STOPS CIRCULATING
IT PAYS FOR WAGES, TAXES, / MATERIALS AND BRINGS
COUNTLESS BENEFITS TO / EVERY BUSINESS

Bronze, 37 mm, 3.04 gm
Golden Gate Bridge, Bay Bridge, Treasure Island / 1940
SAN FRANCISCO / TREASURE ISLAND
GOLDEN GATE INT. EXPOSITION
Struck on a 1936-D Lincoln cent