The bomb was discovered just before 6 p.m. at a level crossing in Nafferton, a village near the Yorkshire coast, the Driffield Times and Post reported. It appeared to be a 2-pound aircraft bomb dropped during World War II.
An army bomb disposal unit declared the bomb inert, Inspector Andrew Dixon of Humberside police said.
Rail service between Driffield and Bridlington was halted for almost 3 hours.
"About half a dozen Nafferton in Bloom stalwarts were digging this afternoon, presumably creating a new garden, and they found it, apparently," a village resident said.