12th Century Coins
In england all currency was based on a single coin - the silver penny. Most close european countires operated the same way too. The english penny showed a picture of the king (or ruling queen) and their name on one side, and a design of a cross on the other side, ringed by text describing which moneyer was in charge of making the coin, and where they were located (ie their mint). (Z) When smaller change was required, a penny could be cut into a half or quarter penny along the lines of the cross design. However these coins were easier to shave silver off than whole pennies, so people prefered to keep coins whole where possible.
Silver pennies were, as the name suggests, made from high quality silver (92.5% pure), and the english penny was considered desireable throughout europe because of it's high quality both in purity, in weight (coins were a fairly consistant 22.5 grains - 1.46g) and in manufacture (making forging and coin clipping harder). (Z) The french penny was less well made and pure, so was consequently worth less than an english penny. (Holmes) Occasionally gold coins from byzantium would reach western europe, and might be used, however this was very rare, and coins would have to be traded to a moneyer into silver pennies.
Every couple of years the english king would issue new dies for the stamping of coins to his official moneyers, with a slightly different design of cross. In the first half of the 12th Century, when this occured, all old currency from the previous type (pattern) was required to be exchanged for the new design at the local moneyer. (Z) This melting down of old coins kept the currency more pure and of accurate weight (thus producing the good reputation of english "sterling" pennies) and also kept the moneyers busy. After securing his rule, King Stephen changed this so that older issue coins were still valid, thus saving money by reducing the number of moneyers.(Z)
The source of silver for coins was actually mostly from coins obtained from continental europe, gained in surplus for trade.(Z) People often hoarded coins in jars, thus creating shortages in coin. For everyday items, especially in villages, barter was more often used than coins, due to their low availability and high value. (Holmes)