shucks!

shucks

1. A mild exclamation of anger, annoyance, regret, or disgust (about something). Typically preceded by the interjections "ah" or "aw." Shucks! I thought that would fix the problem with the computer, but I guess something else must be wrong. Ah, shucks—that was supposed to be a surprise for your birthday!
2. A mild exclamation of humility or embarrassment, especially when receiving praise or flattery. Typically preceded by the interjections "ah" or "aw." A: "I wanted to give you this gift as thanks for everything you did for me and my family." B: "Aw, shucks. I was only doing my duty, ma'am." I've been thinking long and hard about what I would say if I won this award, but now that I'm here, well, shucks—I'm downright speechless!
3. noun Something of very little value. Used especially in the phrases "not worth shucks" and "not amount to shucks." All their promises won't amount to shucks if they aren't willing to back them up with action. I learned long ago that people like him aren't worth shucks.
See also: shuck
Farlex Dictionary of Idioms.

(Ah) shucks!

 and (Ah) shoot!
Rur. Darn! (A mild oath.) Ah, shucks! I forgot to call Grandma. Tom: We can't get chocolate ice cream. The store's all out. Jane: Shucks. Ah, shoot! I missed my favorite TV show.

(Aw) shucks!

Rur. Gosh!; a mild oath. Shucks, ma'am. It wasn't anything at all. Aw shucks, I ain't never been this close to a woman before.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

shucks!

verb
See Aw shucks!
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • shoot
  • ah
  • (my) goodness
  • ach du lieber
  • almighty
  • (for) land('s) sake(s) (alive)
  • Land o' Goshen!
  • (oh) (my) gosh!