Another word which sounds just like what it means.  Almost half of these bumps are from Chapter 9.

• 03.012 or bumped his nose on the pony’s neck.
• 04.045 said poor Mr. Baggins bumping up
• 04.051 bumped his head on hard rock,
• 05.008 not when their heads have recovered from being bumped.
• 05.144 and avoid being bumped into,
• 05.145 who could not make out what he had bumped into,
• 07.108 and had rolled down with a bump from the platform on to the floor.
• 08.059 bumping crash into trees,
• 09.011 or for fear of being bumped into
• 09.029 one of them bumped into another,
• 09.038 and the bumping they would get inside,
• 09.049 Down they go, down they bump!
• 09.050 and a bump,
• 09.056 and bumping mass of casks
• 09.061 though a few went on to bump against the stony pier.
• 13.015 when Bilbo fell forward down the step with a bump into the hall,