With the letter "M", it's way more difficult to make a list, but for some obvious reasons, I couldn't resist, so here's mine:
20. Mine
19. Mandarin
18. Mint
17. Merchant Guild
16. Mystic
15. Merchant Ship
14. Market Square
13. Mining Village
12. Market
11. Masterpiece
10. Moat
9. Moneylender
8. Monument
7. Militia
6. Menagerie
5. Minion
4. Marauder
3. Margrave
2. Mountebank
1. Masquerade