If it weighs 70# or less and domestic, USPS priority mail worked for me. There is a size limitation also
I sent a ~60lb box of tools earlier this year from CA to NM. I got a large Costco Tote to pack them all in. Cost about $80-$90...sent on Friday arrived on Tuesday as I recall. You have to take packages that size into a Post Office.
With the Post Office you can send it General Delivery to a Post Office and pick it up from there...I think you need have to give a 2 week window or something...they won't keep it forever...but they will forward it on to another Post Office if you can't pick it up. This is done a lot by thru hikers for resupply and bounce boxes.
You can also send a package via UPS up to 150# also with size limitations. I think the prices are similar but for some reason I found it less convenient or more limited or something.