Almost certainly Mulberry.

Regardless of your pruning, the shape of the plant is quite unlike Sassafras.

Sassafras and Mulberry are so completely unrelated that grafting wouldn't be possible anyway.

Close up of leaves

@smivies I ruled out mulberry because the results I saw all said they had berries. In my 3 years at this house I've never seen berries on the tree. Answer still stand?

They are common and nothing special, no? I have ripped out a few plantings from the PO and lived to regret doing so. Due to its position I hadn't intended to take any care in digging it out but if it is worth saving I would probably try and give it away on craigslist.

Male mulberries have no fruit. Regardless, still looks like one, and definitely is very much too close to the foundation!

what horster said. This mulberry was brought to this country during the Colonial Era with the hopes of starting up a silk industry. Now it is a permanent weed and spreads a disease that kills off our native mulberry and pollutes its gene pool.
Pull it out, every bit of it and into the compost pile.

@lmich9 - No fruit doesn't mean much...Mulberry can be dioecious (male OR female plants) or monoecious (flowers of both sexes on the same plant). Looks like you have at least one male.