Lily Pad Mew RARE released in 1997 at the Pokemon Jr Stamp Rally in Japan. Graded 6 out of 10 by PSA.
 
Found online from a fellow collector in 2011.
Value: $30-$40

 When this Rally was going on in Japan (1997) they let children visit booths and collect / buy stamps. If they collected enough, they could redeem them for two promo cards: Lily Pad Mew & Surfing Pikachu. That makes this Mew one of the earliest Pokemon cards ever produced!