What happens if I'm 17 and got caught shoplifting more than $100 worth at a grocery?

At age 17, you are an adult in the court system. The maximum potential penalty in Missouri for misdemeanor (under $500) shoplifting is a fine of $1,000 and 1 year in jail. I suggest that you hire an attorney to represent you if you want to avoid ending up with a conviction for stealing/shoplifting. A conviction for shoplifting will prevent you from getting a job, renting an apartment, getting a loan, etc. Depending on which court your case is in, it probably won't cost more than a few hundred dollars to hire an attorney to represent you for the shoplifting case. An experienced attorney can get the charge dismissed or reduced to a lesser offense, such as "Littering."