Generally, a company's samples are the company's property. If there is no contract, then the representative would have to return them on demand (just as the representation could be terminated entirely on demand, in the absence of a contract to the contrary), though the company would have to pay any shipping, insurance, etc. costs. Often, it's not economically worthile to do this and the samples are left with the sales representative, but that is a cost-benefit issue, not a legal one. (And similarly, if the rep will not return the samples voluntarily, it may not be economically worthwhile to bring a legal action to recover them or their value.)