Anyone else have kiddos who lie A LOT?

It's really frustrating because he lies about everything he's only 10 and I know children tell stories and make things up, but no other child i have met lies this much about so many things.

He agrees to something and then a few minutes later it's "I never said that". Or he'll tell a story that is just an outright lie and will try his damn hardest to make you think it's true. You can literally watch him do something, even something small like put a jacket in, and he'll tell you "I didn't put that on. I've been wearing it all day." I watched him push our other foster child over the other day, he was literally stood in front me. I told him to not do that, and he says "I didn't push him". I told him that I just saw him do it and he replies, "no you didn't". I couldn't be bothered with the fight so i told him that I know what I saw and if he did it again, there'd be a consequence. I then hear him a minute later whispering to the child he pushed saying "if you play with me, I won't push you again" So I questioned this, I told him I just heard him admit it and he says to me "I never denied pushing him". I know it sounds small and petty, but it's honestly exhausting.

It's really starting to grate on me. He's only been here two weeks, and I'm struggling. I don't trust a word he says about anything because I know that 99% of what he says in a day just isn't true. I've mentioned it to the SW and all I've got back is "yeah, kids lie!" but do they really lie this much??