From early June until August, we have British summer black truffles available in the UK. These are actually quite common (if you know where to look!), and are therefore considerably less expensive than black winter truffles.
Firstly, summer truffles should be quite dense and quite firm to the touch. When cut in half, they should have a clear marble interior.
The best way to store them is in risotto rice, in the fridge in an airtight container. This means two things: firstly, the truffles become slightly drier, and therefore slightly stronger in flavour, and secondly, you get truffle flavoured risotto rice to use at a later date!
There are numerous ways to use the truffle to best effect. The simplest being shaved thinly over eggs, either scrambled, or very lightly fried in butter. Alternatively, use that rice to make a beautiful mushroom risotto, then shave the truffles over the finished dish!
Other ways include using them to finish a meat sauce, or sliced and stored over a soft cheese to get truffled cheese!
The most important thing to remember is that cooking them will destroy most of the subtle aromas. The residual heat from shaving them over a dish is quite enough, and anymore heat will kill the flavour/aroma. So try and think of them as more of a seasoning than an ingredient!