TASK DEFINITION: You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
PROBLEM: Category: DESIGN 
Clue: Derived from scutum, the Latin for "shield", it's a shield bearing a coat of arms, or a metal plate around a keyhole

SOLUTION: escutcheon

PROBLEM: Category: 3-D 
Clue: It's the next federal holiday after Memorial Day

SOLUTION: independence day

PROBLEM: Category: WORLD HISTORY 
Clue: Edmund "Crouchback" founded this branch of the Plantagenets that didn't get on well with the Yorks

SOLUTION:
the lancasters