Costco (in Canada at least) has these sweet rubber mats that remind me of the gym. Way cheaper than Amazon since they are heavy as heck! It's flat on the other side :
Mon Chateau Anti-Fatigue Air Cushion Mat, Brown | Costco UK
Silentnight Impress 7cm Memory Foam Mattress Topper, Single
Costco UK
Costco UK
GelPro Elite Premium Comfort Anti-Fatigue Floor Mat | Costco
Paramount Memory Foam Plush Bath Mat in 2 Colours, 60 x 91 cm
Best Step Interlocking Foam Tiles - 9 pack - Costco97.com
Golden Select Providence (Grey) AC4 Laminate Flooring with Foam Underlay
Silentnight Now 5 Zone Rolled Memory Foam Mattress in 3 S...
Best Step Microban Interlocking Comfort Flooring - (61 x ...
Best Step Interlocking Tiles with 10 Borders, 6-pack | Costco
Best Step Microban Interlocking Comfort Flooring - (61 x ...
Costco UK
Norsk Reversible Foam Flooring, 48 sq ft., 24 in. x 24 in. Foam Mats | Costco