Brendan Sherlock, with an address at Manorlands, Trim, Co Meath, removed the items from a bag on a bus travelling from Dublin to Roscommon.
Judge Deirdre Gearty was told at Castlerea District Court that Sherlock and another person had boarded the bus at Dublin Airport and had intended to get out at Longford but missed the stop and got off the bus at Termonbary.
A female passenger who got off at Strokestown raised the alarm when she discovered her property was missing.
Gardai went back along the route and found Sherlock and the other person, who is due before the court on similar charges, waiting to catch a bus back to Longford.
Most of the missing items, including a phone and clothes, were recovered but two rings and €300 in cash was missing and has not been recovered.
Judge Gearty said it was a despicable crime. He said Sherlock had a dreadful record after being told he had 116 previous convictions and she jailed him for six months.