As you are aware it is against the law in Iowa, as every other state in the US, to drive without a valid driver's license.
Iowa Code section 321.174 notes in paragraph 1 that a person, except those expressly exempted, shall not operate any motor vehicle upon a highway in this state unless the person has a driver's license issued by the department valid for the vehicle's operation.
If you were ticketed for being unlicensed but in fact just did not have it in your possession at the time of the citation for driving without a license than paragraph 3 of this section of the IA Code would apply.
Here it states that a licensee shall have the licensee's driver's license in immediate possession at all times when operating a motor vehicle and shall display the same, upon demand of a judicial magistrate, district associate judge, district judge, peace officer, or examiner of the department. However, a person charged with violating this subsection shall not be convicted if the person produces in court, within a reasonable time, a driver's license issued to that person and valid for the vehicle operated at the time of the person's arrest or at the time the person was charged with a violation of this section.
If you instead have not ever obtained a driver's license and was caught operating a vehicle than you would be able to be penalized under section 321.218 of the IA Code it appears. Here it notes that a person that operates without a valid driver's license commits a simple misdemeanor. It is also noted here that in addition to any other penalties, the punishment imposed for a violation of this subsection shall include assessment of a fine of not less than two hundred fifty ($250) dollars nor more than one thousand five hundred ($1500) dollars.
Also if someone allowed you to drive their car knowing that you did not have a valid driver's license that car owner could also be penalized by the state of Iowa. IA Code section 321.220 is titled permitting unauthorized person to driver. Here Iowa law states that a person shall not knowingly authorize or permit a motor vehicle owned by the person or under the person's control to be driven upon a highway by a person who is not issued a driver's license valid for the vehicle's operation.
A person convicted of a violation of this section of the Iowa Code is guilty of a simple misdemeanor punishable as a scheduled violation under section 805.8A, subsection 4, paragraph "c." Here it states that for violations under sections 321.174, 321.216B, 321.216C, 321.219, and 321.220, the scheduled fine is one hundred ($100) dollars.
To find out if there are other penalties that could be applied beyond being fined between $250 and $1500, you should contact the court listed on the citation for driving without a license.
If you have never been licensed you may want to contact the Iowa Office of Driver Services to find out if a conviction for being unlicensed will affect your ability to get a driver's license in the future.