People with physical disabilities have ranked object retrieval as a high-priority task for assistive robots. We have developed Dusty, a teleoperated mobile manipulator that fetches objects from the floor and delivers them to users at a comfortable height. In this paper, we first demonstrate the robot's high success rate (98.4%) when autonomously grasping 25 objects considered being important by people with amyotrophic lateral sclerosis (ALS). We tested the robot with each object in five different configurations on five types of flooring. We then present the results of an experiment in which 20 people with ALS operated Dusty. Participants teleoperated Dusty to move around an obstacle, pick up an object and deliver the object to themselves. They successfully completed this task in 59 out of 60 trials (3 trials each) with a mean completion time of 61.4 SD=20.5 seconds), and reported high overall satisfaction using Dusty (7-point Likert scale; 6.8 SD=0.6). Participants rated Dusty to be significantly easier to use than their own hands, asking family members, and using mechanical reachers (p < 0.03, paired t-tests). Fourteen of the 20 participants reported that they would prefer using Dusty over their current methods. Implication for Assistive Technologies A simple robot hand can effectively pick up a wide variety of objects relevant to people with motor impairments from common flooring. A relatively low cost, compact mobile robot can use a simple hand and a vertical lift to pick up and deliver dropped objects to people with motor impairments. In a laboratory setting, people with motor impairments were able to use a semi-autonomous mobile robot named Dusty to successfully pick up an object from the floor and deliver it. Participants reported high satisfaction with the robot Dusty, and on average they reported that it was easier to use than their current methods.