Can you still get sickle cell trait if you're only 1/4 black?

Yes. Sickle trait is when one of your genes for red cell formation is the sickle gene (s). If either of your parents, irrespective of race, carries the trait gene then you have a 50% chance of getting that gene. The chance of a parent having one s is much higher if he/she is black. But some whites do carry the trait gene.