The are nice, big, hefty coins, and a curious thing is happening with them, described below. From a numismatic (coin collecting) point of view, their value is very low. Since they are modern coins (post-1948), and since they are made of non-precious metal (bronze), they command very little collector value. All dates are worth far less than $1 US dollar in circulated condition. If you can find a coin that is fully, absolutely uncirculated, a collector might pay up to $5 US dollars for it, probably less.
The same goes for the modern British half cent. It has a spiffy sailing ship on the reverse, and collectors pay a few US dollars for uncirculated specimens.
The curious thing is that it takes about 50 one cent coins to make a pound of copper. Likewise, it takes about 100 half cents to make a pound of copper. At this writing, copper is trading around $3.75 US dollars per pound (see kitconet.com). So if you can get 50 British pennies for less than $3, you are doing well. Similar things are happening in the US for copper cents.
The UK and US changed the size and composition of their copper coins in the mid to late 1970s. Be careful about getting ideas of melting down your copper coins. It is illegal to do so.