Wierd noise

I have a 1996 oldsmobile achieva, and when i leave for work in the morning i get this wierd noise when i hit a bump or dip in the road sounds like a grinding noise, my achieva is a 2 door sc, and when it warms up the noise slowly goes away...sounds like it maybe something in the steering column or something external, i can feel the noise by my feet and in the steering wheel