James, your coin in average circulated condition with tainted eye appeal is worth a dollar or two US. Eye appear means a lot to coin collectors, and they won't pay high prices unless eye appeal is way up. The 20 centavos in the picture is in beautiful uncirculated condition with plenty of eye appeal.
Here is a summary of approximate catalog values for these coins. These values apply to all dates except as noted.
10 CENTAVOS (0.048 troy ounces silver content)
worn: less than $1 US dollar approximate catalog value
average circulated: $1
well preserved: $3
fully uncirculated: $7
10 centavos dated 1937 are more rare. They are worth five times these values
20 CENTAVOS (0.096 troy ounces silver content)
worn: $1 US dollar approximate catalog value
average circulated: $2
well preserved: $5
fully uncirculated: $15
20 centavos dated 1944 and 1945 are very common. They are worth one-tenth of these values
50 CENTAVOS (0.241 troy ounces silver content)
worn: $5 US dollar approximate catalog value
average circulated: $7
well preserved: $10
fully uncirculated: $16
Use our Important Terminology link to gain an understanding of converting catalog values to actual values.