FALSE PLURALS I

Credit: Washington Post Crossword
Rich Norris
DAMAGED GOODIES (adapted)

The plural of PART is PARTS, but if you incorrectly spelled the plural as PARTIES, you would have a valid word (the plural of PARTY), but a false plural of PART. Can you think of any other words that would yield false plurals in this way?

(Possible) Answers:

BOOK - BOOKIES
TREAT - TREATIES
BEAN - BEANIES
COOK - COOKIES 

NOTE: For examples of false comparatives and false superlatives, see:

BRAIN GAMES IV - posted Jan. 29, 2015 
BRAIN GAMES VI -  posted Jan. 31, 2015
FALSE COMPARATIVES - posted Feb. 19, 2015