All credit goes to YouStayClassy for his guide on
xbox360achievements.orgThe collectibles are:
New York Museum of Natural History level
-20 Museum Magnets
-3 Gum Pack
Smithsonian level
-2 Postcards
Federal Archives level
-8 Souvenir Documents
National Air And Space Museum: Air Section
-8 Pilot Wings
National Air And Space Museum: Storage Section
-17 Wrenches
Washington Art Museum
-12 Paint Tubes
National Museum of Natural History
-10 Bones
(PENNIES DO NOT COUNT FOR THIS ACHIEVEMENT. THIS IS ONLY FOR THE COLLECTIBLES.)