Is there overnight semi truck Parking

I believe so https://www.allstays.com/c/walmart-oregon-locations.htm

Probably only if it's a Walmart truck

There is no overnight parking in the City of Springfield or Eugene, that said I have seen people staying overnight in the parking lot. I was told by the people who were staying there overnigh "don't cause any trouble and you'll be all right" and I'll bet semis for pull in there has plenty of space and stay overnight.