No good unless it's the waterproof stuff most cheap ones are made from MDF or similar and will as already said swell and be no good. Not only that there's a lot of nasty chemicals used in the manufacture of laminate flooring would you really want that leaking into the soil and your plants ??
Yep, it's all just MDF with a micro-thin plastic layer. Wouldn't last 2 minutes, nor be strong enough to retain a bed of soil.
My mate has a fencing business and I'm always there scavenging loads of wood. It costs him 15 quid a ton to get rid of it to a wood recycling place, so he's happy enough for me to collect it as long as I go when they aren't too busy in the yard. Lots of 3x2, 4x2, and some good amounts of 3x3 which are excellent for raised bed posts if sawn or axed to a point at one end. I went yesterday and they had 8 concrete base panels - the 6' x 1' slabs that are commonly used one or two up from ground level in waney-lap type fencing. They weren't new but were an extraction from a job where it's either been gotten rid of, replaced or modified. So one panel had a slight crack in it and they were all dirty and a bit green with moss or mildew or what have you. He was delighted for me to take them as they have to otherwise go in a skip at 130 quid a time. I left the concrete posts of course, all chipped and with a big snot of concrete at one end, but had the panels away quick time. They will be excellent for bed sides, retained with 3x3 posts bashed in the ground either side.
I suggest you scout about in your areas for fencing contractors, especially the ones who are dealing with lots of new-build contracts on the ever-emerging development sites (ie, everywhere). They should have skips and wagons full of offcuts and leftovers and such and should be pleased for someone to relieve their waste bill, now considerable. You need a van of course and an agreement not to get in the way and do all the carrying yourself.