The term "new crop" refers to the new batch of women that come with a girl when she starts dating your friend (ie. her best friends, acquaintances, family members) and that YOU will have the opportunity of meeting. Much like a farmer with a new harvest... Therefore new crop!
Friend A - Bro, I met this fine ass hottie named Emily at the gym...
Friend B - New crop!
Friend A - for sure! Imma hit her up so we can all go out.