Can you get the sickle cell trait from just one parent?

Yes: Persons with sickle trait inherit a normal beta globin gene from one parent and a sickle beta globin gene from the other. They in turn can pass that sickle gene to their children; if this child inherits a normal beta globin gene from the other parent they will have sickle cell trait. If they inherit a sickle gene from the other parent they will have sickle cell anemia.

YES: By definition, a trait comes from only one parent, in that one has inherited a single copy of the defective hemoglobin gene hemoglobin s. If one inheirits the gene from both parents, then one has sickle cell disease, not sickle trait.