I count 5 coins in those pictures...

If for you the only reason you'd keep them is if they're valuable, then no, there's nothing too rare there.
The Arabic one is from Egypt; it's a 5 milliemes of 1973. KM 432, CV 10¢ in VF.
The diamond-shaped Bahamas 15¢ is interesting enough if you want to start an "odd shapes" coin collection, but not too rare. They were actually made for circulation, with a mintage of over a million that year - quite high for such a small country. KM 5, CV $1 in Unc.
The black one is a 1 cent from the Nazi-occupied Netherlands. Interesting enough, if WWII or Nazi puppet states are your thing. It's black and crumbly because it's made of zinc, like most Nazi-occupied coinage is. KM 170, CV 50¢ in VF.
The Spanish 10 centimos looks a bit pale; it may have been cleaned at some stage? KM 675, CV 75¢ in Fine.
Great Britain farthing: 1938 is actually the scarcest year for this type, but that doesn't really affect the price. KM 843, CV 60¢ in EF.
You could give him an album to keep them in...

Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis