If you're in England, then there's a good chance that gold coin is an angel, or, perhaps, a half-angel, part of the new range of gold coinage introduced in the 1460s and 70s by Edward IV. The angel was in essence simply a new issue of the earlier 'noble', which had originally been introduced about a century earlier by Edward III. Unlike Early Medieval English gold coinage like the largely-ceremonial mancus, the angel-noble's value was tied to the value of gold, and in the 15th century, the gold content was repeatedly diminished to maintain its value as the price of gold rose. From the 1460s, however, the angel was introduced to restabilise the currency, and was issued at the original value of the noble, and over ensuing centuries was instead increased in value as the cost of gold rose.

The first value increase of the angel wouldn't occur until 1526 during the reign of Henry VIII, so in 1500, your gold coin would be worth 6s 8d (6 shillings and 8 pence, or 80 pence, one third of a pound). While this isn't an enormous sum, by any means, it might still have represented a considerable amount of money, depending on your wealth and station. Trying to convert medieval sums into modern monetary values is a particularly difficult task, given the many and various ways in which medieval workers may have paid - or indeed been paid - in kind, but for context, a pint of wine (according to the late 14th Century English poem London Lickpenny) would cost you about a penny. J.J. Jusserand estimated the cost of a cow in the 14th Century to be around 9s 5d, so your discovery could also buy you most of a cow. As an interesting point of comparison, Æthelstan's Grately II law code of the 920s established the price of a cow at 20d, which provides a curious illustration of about 5 centuries of medieval inflation.

[As an interesting thought experiment, purely theoretically you could, in 15th century London, exchange a cow for about 110 pints of wine. Based very roughly on current London prices, a cow is equivalent to about 80 glasses of house red, so the exchange essentially still holds up.]

Based on surviving sources such as receipts, bills of sale and household ledgers, your 6s 8d might also purchase you: the brown robes of office of a reeve, about a dozen pairs of boots, six fine hats, about 2 month's rent on a rural cottage [Dyer, 1989], a pair of holsters, 12lb of wax candles or 50lb of cheap tallow candles.