Most reed instruments instruments have keys or finger holes. Most brass instruments have valves. There are brass instruments with keys, though, like the (fairly unsuccessful) keyed bugle. I can find no mention anywhere of a valved reed wind instrument. Does such a thing exist? If not, is there any good reason why it shouldn't?
A typical 3-finger valve cluster only has 7 useful combinations. Brass instruments combine that with vibrating the lips at different speeds so that notes in the harmonic series of any one of those valve combinations are sounded.
In contrast, reed aerophones only vibrate best at the resonant frequency of the instrument as it is configured with the current fingering. If you want to go up or down the harmonic series, you have to vent a tiny hole at the top of the instrument, usually termed the octave or register key. If you try to do this without changing the fingering, you are playing a note that is not stable or in tune.
So essentially, if you stuck a standard valve cluster onto a reed, you would only be able to play 7 different notes. Adding extra valves of various lengths on top of that might be able to expand the theoretical range, but eventually the weight of the extra tubing for each valve would be overwhelming, and the valve combinations for 5-10 fingers would be far more complicated than the Boehm system used on most modern woodwind instruments.
Furthermore, the 3-valve system makes tremendous compromises to get all of the notes in tune, and the notion of adding valves to increase playable range within a single partial introduces more tuning complications than I can even begin to consider.
This is something I've started considering recently (having actually played a tromsoon). Actually, a valved reed instrument would work quite easily. There is no reason to limit the valves to three -- most brass instruments do not.
The best solution to create a valved woodwind would be to use a valve section that takes these issues into account by adding a 4th, 5th, or even 6th valve, as on some professional tubas. These alternate fingerings allow the instrument to play in tune in any register, just as brass instruments do.